REPORT 


ON  THE 

DISPOSAL  OF  THE  SEWAGE 

OF  THE 

CITY  OF  ROCHESTER,  N.  Y. 

BY 

E.  KUICHLING,  C.  E. 
CONSULTING  ENGINEER 


PRESENTED  TO  THE  MAYOR  FEBRUARY,  1907 


Concurred  in  by 
GEORGE  H.  BENZENBERG 
AND 

RUDOLPH  HERING 
CONSULTING  ENGINEERS 


The  M0RRI80N  PRESS 


•  X"2.  &  \  MX\  A'a'aVu  2, 


t„  *.?.■>> 

\e&r 


V 

l 


> 

52  Broadway,  N.  Y.,  Feb.  1,  1907. 


Hon.  James  G.  Cutler,  Mayor, 

City  of  Rochester, 

New  York. 

Dear  Sir: — In  accordance  with  your  request  to  revise  the  recommenda¬ 
tions  made  by  me  in  1889  for  the  disposal  of  the  sewage  of  the  East  Side 
of  the  City  of  Rochester,  and -to  extend  my  review  so  as  to  embrace  the 
sewage  of  the  entire  city,  I  submit  herewith  for  your  consideration  the 
results  of  my  further  studies  of  the  subject. 

In  this  report  I  have  endeavored  to  present  a  statement  of  the  essential 
factors  involved  in  the  problem,  along  with  an  impartial  discussion  of  each 
of  the  various  modes  of  solution  that  seemed  feasible.  Much  collateral  study 
and  numerous  computations  were  thereby  entailed,  and  by  embodying  the 
results  of  this  work,  the  report  has  greatly  exceeded  its  anticipated  length. 

After  the  first  draft  of  my  report  had  been  prepared,  it  was  submitted 
at  your  request  to  two  of  our  foremost  American  municipal  and  sanitary 
engineers,  Messrs.  George  H.  Benzenberg  and  Rudolph  Hering,  as  well 
as  to  City  Engineer  Edwin  A.  Fisher,  for  criticism.  It  was  then  rewritten 
and  now  includes  the  modifications  deemed  advisable  after  a  number  of 
long  conferences  with  the  gentlemen  mentioned. 

Yours  respectfully, 

E.  KUICHLING. 


Digitized  by  the  Internet  Archive 
in  2019  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/reportondisposalOOkuic 


REPORT 

ON  THE 

DISPOSAL  OF  THE  SEWAGE  OF  THE  CITY  OF  ROCHESTER,  N.  Y., 
BY  E.  KUICHLING,  C.  E„  FEBRUARY  \f  1907. 


POPULATION  AND  AREA  OF  CITY. 

According  to  the  various  official  enumerations,  the  population  of  the  city 
was  81,722  in  1875;  89,366  in  1880;  133,896  in  1890;  144,834  in  1892;  162,608 
in  1900,  and  180,525  in  1905,  not  including  the  recently  annexed  village  of 
Brighton.  These  figures  indicate  that  during  the  past  30  years  there  was  an 
increase  of  98,803  in  the  population,  and  that  this  has  taken  place  at  a  nearly 
uniform  annual  rate.  It  is  also  well  recognized  by  statisticians  that 
the  annual  growth  of  communities  of  this  magnitude  rarely  ever  reduces, 
but  almost  invariably  becomes  larger ;  hence  it  may  be  safely  assumed  that 
the  future  growth  of  Rochester  will  gradually  increase  so  as  to  give  the 
present  municipal  area,  exclusive  of  Brighton,  a  population  of  184,000  in 
1906  and  260,000  in  1925. 

The  total  area  of  the  city  is  now  12,627  acres,  of  which  1,313  acres  are 
occupied  by  parks,  cemeteries,  river,  canal,  etc.,  and  794  acres  are  the  former 
village  of  Brighton.  The  natural  drainage  of  Brighton  is  towards  Ironde- 
quoit  Bay,  and  the  sewage  from  most  of  the  recently  annexed  territory  can¬ 
not  flow  into  the  Genesee  River,,  or  into  any  of  the  existing  outlet  sewers 
of  the  city,  unless  it  is  forced  therein  by  pumps.  As  the  City  Engineer 
is  planning  for  the  disposal  of  the  Brighton  sewage  independently,  it  will 
accordingly  be  omitted  from  further  consideration  here,  and  hence  the 
present  habitable  municipal  area  that  will  be  taken  into  account  is  approx¬ 
imately  10,565  acres. 

There  is,  however,  a  large  extent  of  territory  in  the  townships  of  Gates  and 
Greece,  adjacent  to  the  western  boundary  of  the  city,  which  is  particularly 
well  adapted  for  urban  development,  owing  to  its  excellent  railroad,  canal 
and  sewerage  facilities.  Of  this  an  area  of  5,513  acres  in  the  township  of 
Gates  has  contributed  to  the  cost  of  the  West  Side  Trunk  Sewer,  and  at  least 
300  acres  in  the  township  of  Greece  can  make  use  of  the  new  outlet  sewer 
for  the  northern  district  of  Lake  Avenue.  With  reference  to  the  question  of 
future  population  and  sewage  disposal,  this  territory  should  obviously  be 
regarded  as  likely  to  be  annexed  to  the  city  within  the  next  25  years,  and 
hence  the  future  habitable  municipal  area,  exclusive  of  Brighton,  tributary 
to  the  existing  sewerage  system  will  be  at  least  16,000  acres. 

As  to  the  future  population  of  the  said  territory  adjoining  the  present 
western  boundary  of  the  city,  it  will  certainly  be  conservative  to  assume  that 
it  will  become  about  15,000  within  20  years,  and  it  may  therefore  be  expected 
that  about  the  year  1925  the  total  population  tributary  to  the  existing  outlet 
sewers  will  be  approximately  275,000. 


5 


OUTLET  SEWERS,  WITH  TRIBUTARY  AREAS  AND  POPULATION. 


Of  the  aforesaid  habitable  area  of  10,565  acres  now  within  the  city  limits, 
about  60  per  cent  lies  on  the  east  side  of  the  Genesee  River,  and  40  per 
cent  on  the  west  side.  The  population  is  divided  in  nearly  the  same  propor¬ 
tions,  61.6  per  cent,  being  on  the  east  side  and  38.4  per  cent,  on  the  west  side. 
The  sewage  from  the  entire  population  is  at  present  discharged  into  the 
river  through  eight  main  outlet  sewers,  of  which  three  are  on  the  east  side 
and  five  on  the  west  side.  The  areas  and  populations  in  1905  and  1925 
served  by  these  main  outlet  sewers  are  estimated  approximately  as  follows : 


I.  EAST  SIDE. 


Approx. 

area, 


Estimated 

population, 


Acres 

1905 

1925 

East  Main  Street  &  Central  Avenue, 
Lowell  Street,  Evergreen  Street  and 

295 

13,000 

15,500 

Avenue  B, 

543 

14,800 

20,500 

East  Side  Trunk  Sewer,  (inside  city)  4,850 

83,200 

112,500 

Total  sewered,  (inside  city), 

Area  outside  of  city  boundaries  sew- 

5,688 

111,000 

148,500 

ered  by  East  Side  Trunk  Sewer, 
Various  areas  within  city  boundaries 

231 

200 

200 

not  sewered,  but  draining  into  river, 

* 

canal  and  feeder, 

Areas  in  N.  E.  corner  of  city  not  sew- 

684 

100 

250 

ered,  but  draining  into  Irondequoit 
Bay, 

63 

10 

50 

Totals, 

6,666 

111,310 

149,300 

II.  WEST  SIDE. 

4.  Front  and  Allen  Streets, 

5.  Genesee  Valley  Canal  and 

6.  Spencer,  Lyell  Avenue 

Street, 


Total  sewered  (inside  city), 
7b.  West  Side  Trunk  Sewer,  ( 
city), 

8b.  Lake  Avenue, 


187 

4,650 

9,500 

,  1,574 

22,050 

40,500 

L 

783 

24,500 

35,500 

1,047 

14,500 

22,500 

596 

3,700 

6,000 

4,187 

69,400 

111,000 

5,513 

600 

12,500 

300 

100 

2,500 

10,000 

70,100 

126,000 

Totals, 


6 


In  general  terms,  the  average  level  of  the  inhabited  portion  of  the  city 
may  be  regarded  as  being  the  same  as  the  surface  of  the  Erie  Canal.  The 
natural  drainage  of  the  entire  West  Side  and  a  relatively  small  portion  of 
the  East  Side  is  into  the  Genesee  River,  but  by  the  construction  of  the  East 
Side  Trunk  Sewer  nearly  all  of  the  remainder  of  the  East  Side  has  been 
made  tributary  to  the  river.  In  the  southern  half  of  the  city,  the  ordinary 
surface  of  the  river  is  only  from  8  to  20  feet  below  the  surface  of  the  adja¬ 
cent  lands,  but  in  the  northern  half  the  river  flows  through  a  deep  gorge 
with  precipitous  sides.  The  upper  falls,  approximately  100  feet  in  height, 
are  almost  at  the  middle  point  of  the  city ;  the  middle  falls  nearly  30  feet 
in  height,  are  located  about  1.25  miles  northerly;  and  0.25  mile  beyond  the 
latter,  the  lower  falls  have  a  drop  of  nearly  100  feet.  The  total  descent  of 
the  river  in  a  distance  of  4.3  miles  between  the  southern  and  northern 
boundaries  of  the  city  is  about  264  feet,  and  in  the  remainder  of  its  course 
to  Lake  Ontario,  a  distance  of  six  miles,  the  fall  is  very  slight. 

Two  of  the  outlet  sewers  mentioned  discharge  into  the  river  immediately 
below  the  upper  falls,  and  the  remaining  six  discharge  at  different  distances 
northerly.  In  all  cases  the  sewer  terminates  either  in  a  deep  vertical  shaft 
and  short  tunnel,  or  in  a  steel  pipe  laid  on  the  steep  side  of  the  gorge.  The 
location  and  elevation  of  the  bottom  of  each  of  the  said  eight  sewers,  at  or 
near  the  top  of  the  vertical  shaft  or  pipe,  are  given  as  follows,  the  datum  for 


the  elevations  being  about  15  feet  above  the  surface  of  Lake  Ontario : 

Elev.  of 

invert.  Location. 

1.  East  Main  Street  and  Central  Ave., 

-T  221.26 

East  Side,  at  inter¬ 
section  of  Central 
Avenue  and  North 
Water  Street,  near 
upper  falls. 

2.  Avenue  B  outlet  sewer, 

+ 192.09 

East  Side,  at  inter¬ 
section  of  Avenue  B; 
and  St.  Paul  Street,. 
7,000  ft.  N.  of  upper 
falls. 

3.  East  Side  Trunk  Sewer, 

+  151.34 

East  Side,  at  inter¬ 
section  of  Norton 
Street  and  St.  Paul 
Street,  9,450  ft.  N„ 
of  upper  falls. 

3a.  East  Side  Trunk  Sewer, 

4- 162.76 

East  Side,  at  inter¬ 
section  of  Norton 
and  Hollenbeck  Sts., 
9,450  ft.  N.  of  upper 
falls,  and  2,100  ft. 
E.  of  river. 

4.  Front  and  Allen  streets, 

+  190.08 

West  Side,  near  foot 
of  Commercial  St., 
at  upper  falls. 

7 


4a.  Front  and  Allen  streets, 


+  214.89 


5.  Genesee  Valley  Canal  and  Platt  Street,  +199.32 


6.  Spencer,  Lyell  Avenue  and  Saxton  Street, +  202.30 

7.  West  Side  Trunk  Sewer,  +156.31 


8.  Lake  Avenue  (Northern  district)  +128.25 


West  Side,  near  in¬ 
tersection  of  Front 
Street  and  Central 
Avenue. 

West  Side,  at  inter- 
tersection  of  Fac¬ 
tory  and  Mill  Sts., 
1,200  ft.  N.  of  upper 
falls. 

West  Side,  at  foot 
of  Spencer  St.,  3,450 
ft.,  N.  of  upper  falls. 

West  Side,  near  in¬ 
tersection  of  Lex¬ 
ington  Avenue  and 
Hastings  Street  at 
lower  falls,  and 
7,860  ft.  N.  of  upper 
falls. 

West  Side,  at  foot 
of  Lapham  Street, 
5,700  ft.  N.  of  lower 
falls,  12,300  ft.  N.  of 
upper  falls. 


It  may  also  be  remarked  that  when  the  East  Side  Trunk  Sewer  was 
designed  by  the  writer  in  1889,  the  probability  of  a  strong  pollution  of  the 
lower  river  was  foreseen,  and  hence  the  elevation  of  the  invert  of  this  sewer  at 
the  intersection  of  Norton  and  Hollenbeck  streets  was  made  such  that  the 
dry-weather  flow  might  readily  be  diverted  therefrom  by  gravity  to  a  sewage 
purification  works  located  at  a  suitable  place  on  the  East  Side  beyond  the 
city  line.  This  elevation  was  also  chosen  with  the  view  of  intercepting, 
whenever  it  might  become  necessary,  the  dry-weather  flow  of  most  of  the 
other  outlet  sewers  mentioned  above,  and  conducting  the  liquid  by  a  pipe 
and  conduit  to  the  same  purification  works.  The  latter  were  planned  to  be 
on  the  east  side  of  the  river,  because  no  suitable  and  economical  site  could 
be  found  therefor  on  the  west  side. 

No  effort,  however,  was  made  to  secure  the  necessary  land,  as  it  was 
hoped  by  the  municipal  authorities  that  the  dry-season  flow  of  the  river 
would  soon  be  largely  increased  for  the  development  of  water  power  by 
the  construction  of  a  great  reservoir  in  the  vicinity  of  Mt.  Morris  or  Portage 
for  impounding  the  flood  waters  of  the  upper  river.  For  a  time  it  appeared 
probable  that  this  project  would  be  carried  out,  in  which  event  the  sewage 
purification  would  become  unnecessary  for  many  years ;  but  the  expense 
involved  in  the  undertaking  was  found  to  be  so  large  that  its  execution 
has  been  postponed  until  new  demands  for  power  warrant  the  outlay. 
Meanwhile  the  city  has  grown  rapidly,  and  the  pollution  of  the  river  has 
increased  to  such  extent  as  to  compel  attention  to  the  subject  of  the  most 
expedient  manner  of  disposing  of  the  sewage. 

8 


DRY-SEASON  FLOW  OF  RIVER. 


From  the  records  of  the  daily  stage  of  the  river  at  the  Court  Street  dam, 
which  have  been  kept  by  the  City  Engineer  since  1893,  it  is  found  that  on  the 
average  there  is  little  flow  over  said  dam  for  about  five  months  in  the 
year ;  and  from  a  series  of  incomplete  gaugings  of  the  two  upper  races  by 
the  U.  S.  Geological  Survey  in  1903,  it  would  seem  that  during  this  period 
the  discharge  of  the  river  may  range  from  1200  to  400  cu.  ft.  per  second. 
In  fact,  however,  nothing  definite  is  known  of  the  normal  low-water  flow, 
owing  to  the  variable  rates  of  draft  by  the  users  of  the  water  power,  but  it 
might  be  inferred  from  these  data  that  in  ordinary  years  the  discharge  does 
not  fall  much  below  400  cu.  ft.  per  second. 

These  records  indicate  that  low  water  may  occur  during  the  months  of 
February,  June,  July,  August,  September,  October,  November  and  December, 
but  rarely  during  all  these  months  in  the  same  year;  also  that  the  lowest 
average  monthly  flow  during  August,  September  and  October  is  540  cu.  ft. 
per  second;  that  the  average  for  these  three  consecutive  months  is  about  560 
cu.  ft.  per  second;  and  finally,  that  the  least  daily  flow  was  about  510  cu.  ft.  per 
second.  It  should,  however,  be  noted  that  the  observations  of  the  stage  of 
the  water  are  usually  made  in  the  morning  when  the  pool  above  the  Court 
Street  dam  is  replenished  by  the  flow  during  the  night,  and  that  in  the 
dry  season  considerably  lower  stages  occur  soon  afterward  and  prevail  until 
evening.  In  view  of  these  facts,  the  aforesaid  average  monthly  discharges 
of  the  river  must  be  reduced  materially  in  order  to  obtain  the  true  dry- 
season  flow.  From  numerous  gaugings  made  by  the  undersigned  and  others 
in  former  years,  it  may  safely  be  assumeds  that  for  several  weeks  during 
severe  droughts  the  average  flow  will  not  exceed  200  cu.  ft.  per  second,  or 
129,000,000  gallons  per  day,  and  that  in  the  dry  season  of  ordinary  years 
the  least  average  monthly  flow  will  be  about  300  cu.  ft.  per  second,  or 
194,000,000  gallons  per  day. 


DISPOSAL  OF  SEWAGE  BY  DILUTION  IN  RIVER. 

Having  thus  established  the  approximate  dry-season  flow  of  the  river, 
the  question  next  arises  as  to  the  quantity  of  crude  sewage  which  can  be 
discharged  into  the  stream  without  causing  serious  offense  by  disagreeable 
emanations  from  the  channel.  No  argument  is  necessary  to  prove  that 
trouble  of  this  kind  is  likely  to  occur  only  during  the  warm  season,  and  that 
the  processes  of  putrefaction  are  almost  wholly  arrested  in  cold  weather. 
The  consideration  of  the  matter  is  therefore  practically  limited  to  the 
period  from  June  to  November. 

In  forming  a  judgment  as  to  the  discharge  of  crude  sewage  into  the 
river,  the  following  facts  must  be  kept  clearly  in  mind.  Prior  to  the  com¬ 
pletion  of  the  East  Side  Trunk  Sewer  in  1893,  the  sewage  from  about  one- 
half  the  population  on  the  East  Side  found  its  way  into  Irondequoit  Bay, 
while  that  from  the  remainder  of  the  city  was  discharged  into  the  river. 
No  appreciable  pollution  of  the  stream  resulted,  especially  in  the  section 
from  the  lower  falls  to  the  lake,  notwithstanding  the  evidence  of  some 

9 


septic  action  in  the  channel  in  severe  summer  droughts,  and  fish  continued 
to  abound  except  when  destroyed  by  various  trade  wastes,  such  as  the  refuse 
from  gas  works  and  paper  mills.  In  1890  the  population  of  the  city  was 
nearly  134,000,  and  the  crude  sewage  of  about  94,000  persons,  along  with 
nearly  all  the  trade  wastes,  emptied  into  the  river.  The  average  consump¬ 
tion  of  water  was  then  about  63  gallons  per  head  daily,  thus  making  a  dis¬ 
charge  of  about  6,000,000  gallons  per  day  of  crude  sewage  into  the  river 
whose  low-water  flow  did  not  exceed  140,000,000  gallons  per  day.  This  con¬ 
dition  accordingly  represents  a  23-fold  dilution  of  the  sewage,  or  a  minimum 
river  flow  of  138  cu.  ft.  per  minute  for  every  1,000  persons  contributing 
sewage. 

It  should  be  noted,  however,  that  in  1890  the  water  supply  of  the  city 
became  very  limited,  and  that  preparations  were  being  made  for  securing 
an  additional  supply.  The  consumption  of  water  was  therefore  unusually 
small,  thus  making  a  large  ratio  of  sewage  dilution.  After  the  new  water 
works  were  completed,  the  consumption  quickly  increased  to  77  gallons 
per  capita  daily  in  1895,  since  which  time  it  has  steadily  advanced  to  about 
87  gallons  in  1904.  From  1890  to  1900,  and  especially  since  the  completion 
of  the  East  Side  Trunk  Sewer  in  1893,  the  writer  made  many  close  obser¬ 
vations  of  the  condition  of  the  lower  river  during  the  low-water  season 
of  each  year;  and  aside  from  an  offensive  appearance  of  the  water  and 
some  unpleasant  odors  in  the  vicinity  of  the  mouth  of  that  sewer,  due  to  the 
lack  of  properly  mixing  the  sewage  with  the  water  of  the  stream,  he  never 
detected  any  disagreeable  emanations  from  the  river  between  Brewer's  dock 
and  the  lake,  nor  was  he  able  to  find  any  unprejudiced  person  who  had 
noticed  such. 

In  the  autumn  of  1904  the  writer  again  investigated  the  condition  of  the 
lower  river  in  company  with  City  Engineer  Fisher,  and  found  that  while 
the  appearance  of  the  east  side  of  the  channel  from  Norton  street  to  Brewer’s 
dock  had  become  somewhat  more  offensive  than  formerly,  yet  no  disagree¬ 
able  odors  arose  from  the  water  below  the  dock.  Numerous  inquiries  were 
also  made  at  that  time  and  since  of  many  citizens  who  had  traversed  the 
lower  river  more  or  less  frequently  in  boats  during  the  summer,  and  the 
testimony  thus  obtained  was  unanimous  a's  to  the  absence  of  unpleasant 
emanations  from  the  water  in  the  distance  of  5.6  miles  between  the  dock 
and  the  lake. 

.  Complaints,  however,  had  been  made  at  various  times  since  1894  of  the 
occasional  existence  of  disagreeable  odors  in  the  vicinity  of  the  intersection 
of  St.  Paul  a.nd  Norton  streets,  on  ground  whose  elevation  is  from  170  to 
190  ft.  above  the  lower  river,  but  the  investigations  invariably  showed  that 
these  odors  came  from  the  manholes  and  gutter  inlets  of  the  sewers  on  the 
high  ground  mentioned,  and  at  times  also  from  the  mouth  of  the  trunk 
sewer  at  the  river’s  edge.  The  essential  cause  of  the  offense  was  therefore 
“sewer  gas”  or  foul  air  issuing  from  the  sewers,  instead  of  emanations 
arising  from  the  river  after  receiving  the  sewage.  This  is  an  important 
distinction  in  considering  the  question  of  sewage  disposal  by  dilution  with 
river  water. 

It  is  unfortunate  that  accurate  data  concerning  the  low-water  flow  of 
the  river  for  a  long  term  of  years  are  not  available,  especially  since  the 
completion  of  the  East  and  West  Side  Trunk  sewers;  but  in  order  to 


10 


present  some  correct  figures  for  consideration,  it  may  be  stated  that  the 
average  daily  discharges  of  the  river,  computed  from  observations  made 
under  the  writer’s  direction  three  times  each  day  during  the  months  of  July, 
August  and  September,  1888,  ranged  from  7,228  to  9,625  cu.  ft.  per  minute, 
the  mean  being  8,692  cu.  ft.  per  minute,  or  93,630,000  gallons  per  day.  In 
that  year  the  average  daily  consumption  of  water  in  the  city  was  7,745,000 
gallons,  and  the  estimated  population  was  125,000,  of  which  approximately 
87,500  or  70  per  cent,  discharged  their  sewage  and  trade  wastes  into  the 
river.  This  indicates  that  the  sewage  was  then  diluted  about  17-fold  by 
the  river,  or  that  an  average  flow  of  99  cu.  ft.  per  minute  during  the  dry 
season  for  every  1,000  persons  was  able  to  dilute  inoffensively  the  sewage 
of  the  tributary  population.  With  the  said  minimum  flow  of  7,228  cu.  ft. 
per  minute,  the  sewage  was  diluted  only  about  14-fold,  or  an  average  flow 
of  83  cu.  ft.  per  minute  adequately  diluted  the  sewage  of  1,000  persons. 

Similar  observations  of  the  discharge  of  the  river  were  made  by  City 
Engineer  Fisher  in  the  summer  and  autumn  of  1896,  when  the  population 
was  about  153,600,  and  the  average  daily  consumption  of  water  in  the  city 
11,951,000  gallons.  In  that  year  the  East  Side  Trunk  Sewer  was  in  full 
■Operation,  so  that  the  sewage  and  trade  wastes  from  practically  the  entire 
city  were  emptied  into  the  river.  The  writer  is  informed  by  Mr.  Fisher 
that  for  considerable  portions  of  the  time  in  the  dry  season  of  1896  the  flow 
of  the  river  did  not  exceed  12,000  cu.  ft.  per  minute,  or  129,264,000  gallons 
per  day;  hence  the  sewage  was  then  diluted  only  about  11-fold  by  the 
river,  or  a  flow  of  78  cu.  ft.  per  minute  for  every  1,000  persons  was  sufficient 
to  produce  an  inoffensive  dilution  of  the  sewage. 

In  1904  and  1905  the  flow  of  the  river  was  observed  by  the  U.  S. 
Geological  Survey  at  Elmwood  Avenue,  which  is  the  southern  boundary  of 
the  city.  The  gaugings  at  low  water  have  not  yet  been  sufficiently  numerous 
at  this  point  to  establish  the  minimum  flow  with  certainty,  but  it  is  probable 
that  the  same  did  not  exceed  21,000  cu.  ft.  per  minute,  or  226,212,000 
gallons  per  day,  in  these  two  years.  In  1905  the  population,  exclusive  of 
Brighton,  was  180,525,  and  the  average  daily  water  consumption  was 
15,563,000  gallons;  therefore  the  sewage  in  the  dry  season  was  probably 
diluted  not  more  than  14.5-fold,  or  a  flow  of  116  cu.  ft.  per  minute  for 
every  1,000  persons  sufficed  to  make  an  inoffensive  dilution  of  the  sewage 
and  trade  wastes. 

These  results  agree  with  the  extensive  observations  that  were  formerly 
made  by  the  State  Board  of  Health  of  Illinois  with  a  portion  of  the  sewage 
of  Chicago  in  the  Illinois  and  Michigan  Canal  and  the  Des  Plaines  River, 
and  also  more  recently  with  the  bulk  of  the  sewage  of  that  City  in  the  large 
Drainage  Canal.  Other  authorities,  both  in  this  country  and  abroad,  have 
found  that  dilutions  of  14  to  20-fold  were  entirely  satisfactory.  In  a 
paper  read  before  the  American  Public  Health  Association  in  1887,  Mr. 
Rudolph  Hering,  C.  E.,  one  of  the  foremost  sanitary  engineers,  arrived  at 
the  conclusion  that  rivers  which  were  not  used  as  sources  of  domestic 
water  supply  might  receive  the  sewage  from  1,000  persons  for  at  least 
every  150  to  200  cu.  ft.  of  minimum  flow  per  minute,  (or  2.5  to  3.3  cu.  ft.  per 
second),  supposing  that  natural  subsidence  of  the  heavier  matter  takes 
place  immediately  below  the  point  of  discharge.  To  convert  these  figures 
into  terms  of  dilution,  it  may  be  assumed  that  in  American  cities  sewage 


11 


is  produced  (measured  by  the  water  supply)  at  the  rate  of  100  gallons  per 
head  per  day,  which  corresponds  to  9.35  cu.  ft.  per  minute  per  1,000  popula¬ 
tion  ;  hence  on  this  basis  the  rate  named  by  Mr.  Hering  corresponds  to  a 
minimum  dilution  of  from  15  to  21-fold. 

It  may  also  be  remarked  that  the  portion  of  the  river  below  the  lower 
falls  is  particularly  well  adapted  to  receiving  sewage,  owing  to  the  extreme 
aeration  of  the  water  by  the  falls  above,  the  depth  and  uniformity  of  its 
channel,  its  sluggish  current  in  time  of  drought,  and  its  strong  floods  every 
spring.  By  reason  of  these  peculiarities,  a  thorough  sedimentation  of  the 
sewage  takes  place  in  a  long  stretch  of  the  deep  channel  during  the  dry 
season,  and  the  accumulated  deposit  is  scoured  away  into  Lake  Ontario  by 
the  next  high  freshet.  In  warm  weather  the  sediment  undergoes  septic  action 
to  some  extent,  which  is  demonstrated  by  a  copious  evolution  of  bubbles 
of  inodorous  marsh  gas,  but  the  development  of  sulphurated  hydrogen  and 
other  offensive  gases  has  not  yet  occurred  in  appreciable  quantity,  except 
when  the  mud  in  the  shallow  parts  of  the  channel  is  disturbed  by  steam¬ 
boats.  Fortunately,  however,  there  is  little  navigation  in  this  section  of  the 
river,  so  that  annoyances  from  boat  traffic  can  be  left  out  of  consideration. 

From  the  foregoing  statements  and  experiences  concerning  the  disposal 
of  sewage  by  dilution,  it  is  probable  that  the  volume  of  sewage  produced 
by  the  city  has  now  reached  such  a  magnitude,  that  the  ability  of  the  river 
to  absorb  it  without  serious  offense  during  the  season  of  low  water  will 
soon  reach  its  limit;  and  if  the  practice  is  to  be  continued,  it  follows  that 
either  the  low-water  flow  of  the  stream  must  be  increased  in  some  manner, 
or  the  quantity  of  crude  sewage  discharged  into  the  stream  must  be  reduced 
during  the  summer  and  autumn  months  in  proportion  as  the  population  of 
the  city  increases.  In  other  words,  the  river  in  its  natural  state  can  deal 
safely  by  dilution  with  only  a  definite  quantity  of  raw  sewage  during  the 
warm  season,  and  this  limit  has  apparently  been  reached. 


INCREASING  THE  LOW-WATER  FLOW  OF  THE  RIVER  BY 

STORAGE. 

The  flow  of  the  river  during  the  low-water  season  can  be  increased 
either  by  the  provision  of  adequate  storage  for  use  during  four  or  five 
months  each  year,  or  by  diverting  into  its  channel  water  from  another 
source.  The  first  alternative  has  been  under  active  consideration  during 
the  past  16  years,  both  by  the  State  for  canal  purposes,  and  by  private  enter¬ 
prise  for  the  improvement  of  the  water  power,  but  the  great  cost  of  the 
undertaking  has  hitherto  prevented  its  execution.  To  indicate  the  magni¬ 
tude  of  the  storage  that  would  be  required  for  the  proper  dilution  of  the 
city’s  sewage  during  a  period  of  unusual  drought,  it  may  be  assumed  that 
the  average  natural  flow  of  the  river  will  not  exceed  300  cu.  ft.  per  second 
during  six  consecutive  months.  This  quantity  is  computed  from  the  gaug- 
ings  of  the  river  in  1895  near  Mt.  Morris,  N.  Y.,  where  the  drainage  area 
is  1,070  sq.  miles,  on  the  basis  that  the  1430  sq.  miles  of  additional  territory 
between  Mt.  Morris  and  Rochester  contributed  at  the  same  rate  per  square 
mile  as  the  upper  part  of  the  watershed. 


12 


It  may  also  be  assumed  that  in  constructing  the  storage  reservoir  pro¬ 
vision  should  be  made  for  a  population  of  300,000  in  the  city,  with  a  sewage 
discharge  of  30,000,000  gallons  per  day,  or  46.42  cu.  ft.  per  second;  and 
in  order  to  be  conservative,  the  dilution  may  be  taken  at  20-fold,  thus 
requiring  a  flow  of  928  cu.  ft.  per  second.  It  therefore  follows  that  in  a 
year  like  1895,  there  will  be  a  deficiency  of  628  cu.  ft.  per  second  in  the 
natural  flow  of  the  river  for  a  period  of  180  days,  which  corresponds  to  a 
storage  volume  of  nearly  10,000,000,000  cu.  ft.,  unless  a  portion  of  the  defi¬ 
ciency  is  supplied  from  the  Erie  or  Barge  Canal.  As  an  indication  of  the 
cost  of  such  a  reservoir,  it  may  be  stated  that  in  1894,  the  State  Engineer 
estimated  an  outlay  of  about  $2,500,000  for  providing  7,300,000,000  cu.  ft.  of 
storage  in  the  river  gorge  near  Mt.  Morris,  and  in  1896  he  submitted  an 
estimate  of  $2,600,000  for  a  reservoir  holding  15,000,000,000  cu.  ft.  at  Portage. 

It  might  be  urged  that  the  construction  of  such  a  reservoir  would  be 
a  great  benefit  to  all  the  owners  of  water  power  on  the  river,  and  that  they 
should  bear  the  greater  part  of  the  expense.  This  is  perfectly  true,  but  there 
is  no  way  to  compel  such  owners  to  unite  in  the  undertaking,  either 
by  .themselves  or  in  conjunction  with  the  City  or  the  State.  An  organiza¬ 
tion  for  the  purpose  was  made  in  1898,  but  it  failed  to  secure  the  necessary 
backing,  or  even  to  test  the  constitutionality  of  the  rights  given  to  the  com¬ 
pany  by  the  Legislature.  Moreover,  an  enterprise  of  this  magnitude  usually 
requires  several  years  to  harmonize  by  legislation  and  tedious  legal  processes 
the  varied  interests  that  are  involved,  and  several  years  more  will  be  needed 
for  construction;  hence  it  may  be  concluded  that  notwithstanding  the 
attractiveness  of  the  proposition,  the  sewage  pollution  of  the  lower  part  of 
the  river  will  exceed  endurable  bounds  before  the  project  can  be  executed, 
and  that  relief  in  the  meantime  must  be  provided  by  other  means. 

But  even  if  the  river  might  continue  to  receive  the  crude  sewage  of 
the  city  until  the  completion  of  such  a  storage  reservoir,  the  equalized 
flow  of  the  stream  in  years  of  low  rainfall  would  suffice  to  dilute  inoffen¬ 
sively  the  sewage  from  only  a  limited  future  population.  On  the  basis  of 
200  cu.  ft.  of  river  water  per  minute  for  every  1,000  persons  contributing 
sewage,  a  constant  flow  of  1,000  cu.  ft.  per  second  through  the  city  would 
suffice  for  a  population  of  not  more  than  300,000,  and  after  this  limit  is 
reached  it  will  become  necessary  either  to  increase  the  storage,  or  to  devise 
means  for  preventing  a  larger  discharge  of  crude  sewage  into  the  stream ; 
hence  conditions  would  arise  which  are  like  those  now  confronting  the  city. 
It  may  also  be  added  that  the  aforesaid  ratio  of  20  to  1  for  diluting  sewage 
is  regarded  by  Mr.  Hering  as  applicable  only  when  the  most  troublesome 
trade  wastes  are  excluded  from  the  sewers,  and  that  if  no  restriction  in  this 
respect  is  enforced,  a  much  larger  ratio  must  be  taken  to  secure  satisfactory 
results. 

Relief  can  also  be  obtained  after  the  Barge  Canal  is  in  operation,  by  the 
constant  discharge  of  a  large  volume  of  water  therefrom  into  the  river.  The 
only  question  in  this  case  is  about  the  quantity  and  permanency  of  the  sup¬ 
ply  that  may  thus  become  available.  Under  ordinary  conditions  a  surplus 
of  about  300  cu.  ft.  per  second  might  be  counted  on  from  this  source,  but 
circumstances  may  arise  whereby  the  quantity  delivered  would  become  much 
less,  and  in  the  event  of  a  break  in  the  banks  between  Rochester  and  Buffalo, 
the  supply  would  cease  entirely  for  a  time.  It  is  therefore  unwise  to  con- 


13 


sider  that  so  large  an  additional  flow  as  600  cu.  ft.  per  second  can  be  obtained 
permanently  from  the  Barge  Canal,  unless  the  present  plans  for  its  construc¬ 
tion  are  modified.  Furthermore,  the  Canal  is  yet  far  from  completion, 
whereas  the  necessity  for  a  substantial  betterment  of  the  condition  of  the  lower 
river  is  close  at  hand. 

Another  suggested  method  of  improvement  would  be  a  frequent  flushing, 
of  the  lower  river  by  releasing  a  large  volume  of  water  that  might  be 
impounded  periodically  in  the  upper  river  at  some  favorable  locality  above  the 
city;  but  as  such  storage  in  the  dry  season  involves  a  corresponding  large 
reduction  of  the  natural  flow  between  the  intervals  of  flushing,  an  inter¬ 
ference  with  the  rights  of  the  owners  of  the  water  power  would  at  once 
ensue.  To  give  an  idea  of  the  quantity  of  water  that  would  be  necessary 
for  this  purpose,  it  may  be  added  that  the  capacity  of  the  river  channel  from 
Norton  Street  to  the  Lake  at  low  water  is  about  130,000,000  cu.  ft.,  which  is 
7.5  times  the  daily  flow  at  the  minimum  rate  of  200  cu.  ft.  per  second,  and 
5.0  times  the  daily  flow  at  300  cu.  ft.  per  second.  In  order  to  secure  enough 
water  to  renew  the  contents  of  the  5.92  miles  of  channel  between  the  points 
mentioned,  it  would  accordingly  be  necessary  to  wait  for  a  considerable  rise 
of  the  river  by  rains,  and  as  several  weeks  might  elapse  in  a  period  of 
drought  before  such  a  rise  would  occur,  it  follows  that  this  plan  of  flushing 
is  impracticable. 

The  only  way  of  accomplishing  the  purpose  without  seriously  trespassing 
on  the  rights  of  the  owners  of  water  power,  is  to  store  a  sufficient  quantity 
of  flood  water  for  use  during  the  season  of  low  water.  It  is  reasonable  to 
assume  that  s/ich  a  flushing  would  be  necessary  at  least  ten  times  in  the 
course  of  five  jr  six  months  of  warm  weather,  and  hence  a  storage  of  about 
1,300,000,000  cu.  ft.  would  have  to  be  provided.  A  practical  reservoir  site  of 
this  large  capacity,  however,  cannot  be  found  on  the  river  below  Mt.  Morris, 
nor  is  there  between  Rochester  and  Mt.  Morris  an  economical  site  for  a 
reservoir  of  even  one-fifth  of  this  volume.  Without  extensive  preliminary 
surveys  and  computations,  an  accurate  estimate  of  the  cost  of  such  a  reservoir 
in  the  vicinity  of  Mt.  Morris  cannot  be  made,  but  by  comparison  with  the 
cost  of  similar  undertakings  elsewhere,  it  is  probable  that  the  expense  will 
not  be  much  less  than  $900,000.  In  view  of  its  large  cost  and  the  uncertainty 
of  its  effect  in  remedying  the  pollution  of  the  lower  river,  this  plan  cannot 
be  recommended. 


INCREASING  THE  LOW-WATER  FLOW  OF  THE  RIVER  BY 
PUMPING  FROM  LAKE  OR  BAY. 

A  remaining  method  is  to  flush  the  lower  river  by  pumping  the  necessary 
supply  of  water  for  adequately  diluting  the  crude  sewage  of  the  city  from 
the  Lake  or  Irondequoit  Bay.  As  the  shortest  distance  from  the  foot  of  Nor¬ 
ton  Street  to  the  shore  of  the  lake  is  about  the  same  as  to  the  bay,  namely 
4.66  miles  in  a  direct  line,  and  as  the  conduit  would  have  to  be  in  tunnel' 
through  rock  for  practically  the  entire  distance,  there  is  little  choice  between 
these  two  sources.  It  is  also  apparent  that  such  constructions  should  not  be 
frequently  duplicated,  and  that  it  will  be  expedient  to  provide  in  the  outset 


14 


sufficient  tunnel  capacity  to  meet  the  requirement  at  the  end  of  at  least  20 
years,  or  when  the  population  has  become  at  least  275,000.  Additional  pump¬ 
ing  machinery  on  the  other  hand,  may  be  installed  at  intervals  of  about  five 
years. 

On  the  assumption  that  the  population  in  1925  will  be  275,000,  and  that 
each  person  will  then  produce  100  gallons  of  sewage  per  day,  the  dry-weather 
flow  of  the  sewers  will  be  at  the  average  rate  of  42.5  cu.  ft.  per  second;  and 
if  we  assume  that  a  20-fold  dilution  thereof  will  be  needed  in  order  to  keep 
the  lower  river  in  tolerable  condition,  the  flow  of  the  stream  must  be  at  least 
850  cu.  ft.  per  second.  It  will  also  be  assumed  that  the  average  natural  dry- 
season  flow,  along  with  the  surplus  water  of  the  canal,  is  350  cu.  ft.  per 
second  during  a  period  of  120  consecutive  days,  thus  making  it  necessary  to 
supply  an  average  of  500  cu.  ft.  per  second  by  pumping  from  the  lake  or  bay 
through  a  conduit  4.66  miles  long. 

On  investigating  this  proposition,  it  will  be  found  that  the  most  economi¬ 
cal  conditions  will  be  obtained  with  a  smoothly-lined  circular  conduit  or 
tunnel  12.0  ft.  in  diameter,  and  steam  pumping  machinery  operating  centrif¬ 
ugal  pumps  of  high  efficiency.  The  quantity  of  water  to  be  pumped  obvi¬ 
ously  varies  with  the  stage  of  the  river,  and  will  probably  range  from  100 
to  600  cu.  ft.  per  second,  while  the  fixed  grade  of  the  tunnel  is  adapted  to  the 
average  discharge.  When  the  river  is  at  its  lowest  stage,  the  largest  quantity 
of  water  must  be  pumped,  whereby  about  1900  IHP  will  be  required  eventually. 
Under  these  conditions,  including  tunneling  in  rock,  the  costs  will  be 
approximately  as  follows :  For  24,600  lin.  ft.  of  tunnel,  including  7  shafts, 
$1,156,200;  for  steam  engines,  boilers,  centrifugal  pumps  and  accessories, 
adapted  to  develop  1900  IHP,  $117,800;  for  buildings  and  foundations  of 
pumping  station  $30,000;  for  lands  and  rights  of  way  $18,800;  for  con¬ 
tingent  expenses  about  10  per  cent,  of  the  foregoing,  or  $132,200;  total 
$1,455,000. 

In  computing  the  annual  operating  expenses  of  such  a  plant,  in  which 
work  is  done  for  only  four  or  five  months  in  the  year  on  the  average,  it 
must  be  remembered  that  at  least  three  skilled  employees  must  be  retained 
permanently,  and  that  under  the  8-hour  law  three  crews  of  men  will  be 
employed  during  5  months  of  each  year  on  the  average,  as  a  fixed  time  for 
beginning  and  ending  the  work  cannot  be  set.  Basing  the  pumpage  on  the 
use  of  only  724  IHP.  on  the  average  for  120  days,  with  coal  at  $3.00  per 
ton  and  a  consumption  of  3  lbs.  per  horse  power  per  hour,  the  cost  of  the- 
necessary  fuel  will  be  $9,450;  salaries  of  3  permanent  skilled  employees,. 
$3,000;  wages  of  temporary  employees  for  5  months,  $6,000;  station  supplies,, 
maintenance  of  machinery,  etc.,  and  incidentals,  $2,150;  total,  $20,600  per 
year.  This  annual  expense  does  not  include  interest,  depreciation  and  sink¬ 
ing  fund  charges,  and  relates  to  the  time  when  the  population  is  275,000. 

It  will  be  noticed  that  a  20-fold  dilution  of  the  crude  sewage  was 
assumed  in  making  the  preceding  estimate;  but  in  view  of  the  actual  condi¬ 
tion  of  the  lower  river  in  dry  seasons,  it  may  be  urged  that  a  lesser  dilution 
would  produce  entirely  satisfactory  results.  For  the  purpose  of  making  com¬ 
parisons  of  cost,  a  second  computation  was  accordingly  made  on  the  assump¬ 
tion  that  a  14-fold  dilution  would  be  sufficient,  and  that  an  average  pumpage 
of  only  200  cu.  ft.  per  second,  with  a  maximum  of  400,  would  be  required 
during  the  low-water  season  of  120  consecutive  days.  The  results  showed 

15 


that  the  diameter  of  the  flushing  tunnel  should  be  10.0  ft.,  and  that  the 
steam  engines  should  have  a  maximum  capacity  of  920  IHP.,  the  average 
use  being  460  IHP.  during  the  season.  The  total  cost  in  this  case  was 
estimated  at  $1,214,000,  and  the  yearly  operating  expense  at  $16,000  when  the 
population  reaches  the  magnitude  named  above. 

The  foregoing  plan  has  some  attractive  features,  but  is  open  to  the  objec¬ 
tion  that  it  makes  no  provision  whatever  for  improving  the  condition  of  the 
8,500  ft.  of  river  channel  from  the  upper  to  the  lower  falls,  or  in  fact  to  the 
mouth  of  the  East  Side  Trunk  Sewer,  3,100  ft.  below  the  lower  falls.  To 
deliver  the  flushing  water  at  any  higher  elevation  than  the  surface  of  the 
lower  river  is  manifestly  too  expensive  for  serious  consideration,  and  if  the 
tunnel  were  carried  to  the  foot  of  the  lower  falls  where  it  would  serve  for 
diluting  the  sewage  of  the  West  Side  Trunk  Sewer,  the  length  and  cost  of 
the  work  would  be  largely  increased.  The  plan  therefore  entails  the  eventual 
interception  of  the  dry-weather  flow  of  the  outlet  sewers  which  now  dis¬ 
charge  above  the  lower  falls,  in  the  manner  that  will  be  outlined  hereafter, 
and  the  delivery  of  this  flow  either  directly  into  the  flushing  tunnel,  or  into 
the  river  near  the  mouth  of  said  tunnel. 


QUANTITY  OF  SEWAGE  PRODUCED. 


In  a  city  provided  with  an  extensive  system  of  water  works  and  sewers, 
it  is  customary  to  assume  that  in  dry  weather  the  sewage  is  produced  at  prac¬ 
tically  the  same  rate  as  the  water  is  consumed  from  the  various  sources  of 
supply.  The  total  daily  quantity  discharged  may,  however,  vary  considerably 
from  the  daily  water  supply  in  consequence  of  the  lack  of  perfect  water-tight¬ 
ness  of  the  sewers,  whereby  either  a  considerable  loss  of  liquid  may  occur  by 
leakage  into  a  porous  and  absorptive  subsoil,  or  an  appreciable  gain  may  ensue 
by  the  infiltration  of  ground-water.  In  the  case  of  Rochester,  no  systematic 
gaugings  of  the  discharge  of  the  various  outlet  sewers  have  been  made ; 
but  as  most  of  them  are  excavated  in  the  underlying  rock,  and  as  they  also 
intercept  whatever  seepage  occurs  from  the  Erie  Canal  which  passes  diagon¬ 
ally  through  the  city,  it  will  be  safe  to  consider  that  the  dry-weather  flow  of 
sewage  is  somewhat  greater  than  the  water  supply. 

During  the  eight  years  from  January  1,  1895,  to  January  1,  1903,  the 
average  consumption  of  water  from  the  public  supply  gradually  increased  from 
77  to  94  gallons  per  capita  daily,  and  in  the  next  two  years  it  was  reduced 
to  87.  For  the  entire  10-year  period  the  average  was  84  gallons  per  capita 
daily,  and  in  1904  the  mean  daily  consumption  was  15,238,000  gallons.  It  is, 
however,  highly  probable  that  the  per  capita  consumption  of  water  will 
gradually  increase  in  the  future  as  in  the  past,  although  it  may  be  checked 
temporarily  by  the  application  of  meters,  or  by  various  other  causes ;  and 
hence  it  will  be  assumed  that  in  the  course  of  the  next  twenty  years  this 
consumption  will  advance  so  that  the  dry-weather  flow  of  sewage  and 
infiltering  ground-water  will  be  about  100  gallons  per  head  daily.  This  quan¬ 
tity  was  adopted  in  the  preceding  estimates,  and  will  be  retained  for  com¬ 
puting  the  sizes  of  the  various  pipes  and  conduits  involved  in  other  plans. 


16 


MECHANICAL  AND  CHEMICAL  CLARIFICATION  OF  SEWAGE. 


If  the  crude  sewage  of  a  city  cannot  be  discharged  continuously  and 
inoffensively  into  a  large  river,  a  considerable  improvement  in  the  appear¬ 
ance  of  the  stream  during  the  low-water  season  can  be  secured  by  removing 
from  the  sewage  more  or  less  of  the  solid  organic  matter  which  it  carries  in 
suspension.  Such  removal  may  be  accomplished  either  by  mechanical  or 
chemical  means,  and  the  resulting  clarified  liquid  can  then  be  discharged 
inoffensively  into  a  correspondingly  smaller  flowing  stream  than  is  required 
for  the  satisfactory  dilution  of  crude  sewage.  This  is  equivalent  to  stating 
that  each  unit  of  volume  of  relatively  clean  river  water  can  receive  a  certain 
maximum  quantity  of  organic  matter  from  sewage  without  becoming  offensive 
to  sight  and  smell,  and  it  becomes  important  to  ascertain  this  limiting  quantity 
in  the  case  under  consideration. 

It  was  shown  in  the  foregoing  that,  aside  from  the  unsightly  conditions 
at  the  mouth  of  the  East  Side  Trunk  Sewer,  the  water  of  the  lower  river  has 
not  become  noticeably  malodorous  when  mixed  with  crude  sewage  in  the 
proportion  of  14  to  1  by  measure  or  volume,  and  that  in  1904  and  1905  the 
sewage  was  discharged  into  the  river  at  the  average  rate  of  86  gallons  per 
head  of  population  per  day.  Unfortunately  no  chemical  analyses  of  the 
sewage  of  Rochester  are  available ;  but  as  there  is  no  reason  for  considering 
that  it  differs  materially  in  composition  from  the  sewage  of  other  large  cities, 
it  can  be  assumed  that  on  the  average  the  total  quantity  of  dry  volatile  matter, 
or  “loss  on  ignition,”  in  the  liquid  amounts  to  about  100  grams  or  3.53 
ounces  per  capita  daily,  of  which  55  grams  or  1.94  ounces  are  dissolved  and 
45  grams  or  1.59  ounces  are  suspended  in  the  water.  This  dry  volatile 
matter  is  regarded  as  being  approximately  the  quantity  of  organic  matter  of 
every  description  contained  in  the  sewage,  but  it  must  also  be  remembered 
that  some  of  it  consists  of  soot,  coal,  coke,  wood  and  other  organic  sub¬ 
stances  which  are  not  offensive  or  putrescible. 

As  to  human  excreta,  the  usual  average  figures  for  a  mixed  population 
of  adults  and  children  of  both  sexes  are  0.63  ounce  of  dry  fecal  matter 
mostly  in  suspension,  and  1.52  ounces  of  evaporated  urine  in  solution,  per 
capita  daily.  Of  these  quantities  about  4  and  2  per  cent  respectively  are 
mineral  matters,  thus  leaving  2.09  ounces  of  organic  matter,  of  which  1.61 
ounces  or  77  per  cent,  is  dissolved;  and  on  comparing  these  figures  with 
those  previously  given  for  the  total  dry  organic  matter,  it  will  be  seen  that 
at  legist  1.11  ounces  of  dry  suspended  and  0.33  ounce  of  dry  soluble  organic 
matter  per  capita  daily  are  derived  from  other  sources  than  human  excreta. 

With  •  14-fold  dilution  and  86  gallons  of  crude  sewage  per  head,  the 
river  water  thus  contains  in  the  dry  season  about  3.53  ounces  of  dry  organic 
matter  in  every  1,290  gallons  flowing  to  the  lake;  or  expressed  otherwise,  a 
population  of  178,000  in  1904  discharged  daily  19.63  tons  of  dry  organic 
matter  into  the  river  whose  dry-season  flow  including  the  sewage  was  probably 
not  more  than  355  cu.  ft.  per  second,  and  of  this  matter  10.79  tons  were 
dissolved,  and  8.84  tons  were  suspended  in  the  water.  As  it  is  probable  that 
the  lower  river  cannot  be  polluted  to  a  much  greater  degree  without  giving 
rise  to  disagreeable  emanations,  these  figures  may  accordingly  be  adopted  as 
limits  beyond  which  it  will  be  unsafe  to  go. 


17 


Concerning  the  relative  offensiveness  of  the  putrescible  organic  matters 
which  are  carried  in  solution  and  suspension  in  the  sewage,  little  seems  to 
be  known  at  the  present  time,  except  that  the  suspended  matter  is  generally 
regarded  as  being  much  more  objectionable  than  the  dissolved  matter.  The 
latter  is  absorbed  by  algae  and  is  also  rapidly  oxidized  or  changed  in  char¬ 
acter  by  numerous  aerobic  organisms  in  open  streams,  whereas  the  solid 
matter  is  attacked  slowly  and  by  sinking  to  the  bottom  of  the  channel,  it  is 
cut  off  from  exposure  to  the  air  and  left  to  undergo  putrefactive  decomposi¬ 
tion.  In  this  process  a  certain  amount  of  the  settled  matter  is  liquefied  and 
marsh  gas  is  evolved,  whereby  a  considerable  degree  of  purification  is  effected 
in  water  of  moderate  depth. 

In  view  of  the  general  opinion  that  the  suspended  organic  matter  is  much 
more  offensive  in  a  stream  than  that  which  is  in  solution,  and  in  the  absence 
of  any  definite  observations  in  this  respect  other  than  practical  experience 
with  the  effluents  of  precipitation  works  and  a  number  of  experiments  made 
by  the  writer  some  years  ago,  it  may  be  assumed  that  the  sewage  water  can 
be  divided  into  two  equal  parts  of  43  gallons  per  capita  each,  and  that  a 
10-fold  dilution  of  the  part  containing  the  dry  soluble  organic  matter  will 
suffice  to  prevent  disagreeable  emanations  from  the  water,  while  a  20-fold 
dilution  is  necessary  in  the  case  of  the  part  containing  the  dry  suspended 
organic  matter.  With  these  dilutions  the  resultant  flow  of  the  river  would 
be  10  x  43  equals  430  gallons  for  1.94  ounces  of  dissolved  dry  organic  matter, 
and  20  x  43  equals  860  gallons  for  1.59  ounces  of  suspended  dry  organic  matter, 
or  a  total  of  1,290  gallons  for  the  aforesaid  total  of  3.53  ounces  per  capita 
daily,  corresponding  to  the  addition  of  14  parts  of  relatively  clean  water  to 
one  part  of  crude  sewage. 

The  liberality  of  the  preceding  estimate  for  the  inoffensive  dilution  of 
the  dissolved  and  suspended  organic  components  of  sewage  will  be  appreciated 
by  a  few  comparisons.  In  many  of  the  English  and  European  cities  the 
sewage  is  much  stronger,  or  smaller  in  volume  per  capita,  than  in  American 
cities,  and  is  purified  by  chemical  treatment,  by  which  about  two-thirds  of 
the  suspended  matter  and  more  than  one-half  of  the  organic  matter  therein  are 
removed.  The  effluents  in  these  places  discharge  into  small  streams  whose 
dry-weather  flow  is  often  only  a  few  times  greater  than  the  volume  of 
partially  clarified  sewage,  and  no  offensive  condition  of  the  stream  ensues. 
The  same  observation  has  also  been  made  with  the  effluent  of  the  sewage 
works  of  Worcester,  Mass.,  as  the  writer  was  recently  informed  by  Dr.  Id.  P. 
Eddy,  who  has  had  charge  of  these  works  for  the  past  ten  years,  that  when 
the  flow  of  the  Blackstone  River  was  from  8  to  10  times  larger  than  the 
discharge  from  the  precipitation  tanks,  the  stream  remained  in  excellent 
condition.  It  must  also  be  remembered  that  a  20-fold  dilution  for  very 
strong  crude  sewage  has  been  found  adequate  in  many  cases,  and  it  cannot 
be  presumed  that  as  much  diluting  water  is  needed  for  a  part  of  the  organic 
matter  as  for  the  whole. 

On  the  basis  mentioned  above,  the  removal  of  the  whole  of  the  suspended 
organic  matter  from  the  sewage  would  leave  the  same  quantity  of  river  water 
capable  of  diluting  inoffensively  the  dissolved  organic  matter  from  3.22  times 
as  many  people  as  before;  and  if  two-thirds  of  the  suspended  organic  matter 
were  removed,  the  same  quantity  of  river  water  would  render  inoffensive 
the  rest  of  the  matter  in  the  sewage  of  1.87  times  the  number  of  persons. 


18 


Similarly,  if  one-half  of  the  suspended  organic  matter  were  removed,  the 
sewage  of  about  1.54  times  as  many  people  would  be  adequately  diluted;  if 
one-third  were  removed,  the  resultant  dilution  would  suffice  for  1.31  times 
as  many  people;  and  if  one-fourth  were  removed,  the  dilution  would  suffice 
for  1.22  times  as  many  people  as  before. 

It  is  thus  seep  that  with  a  steadily  increasing  population  the  sewage 
pollution  of  the  lower  river  can  be  maintained  at  a  certain  constant  degree, 
defined  by  the  absence  of  offensive  emanations  from  the  water,  if  a  gradually 
increasing  proportion  of  the  suspended  organic  matter  in  the  sewage  is 
removed  from  either  a  part  or  the  whole  of  the  liquid  before  allowing  it  to 
discharge  into  the  river,  and  also  if  a  thorough  mixture  of  the  sewage  with 
the  river  water  is  secured.  The  recognition  of  this  fundamental  principle  is 
a  matter  of  great  importance,  so  far  as  the  cost  of  permanently  improving 
the  present  condition  of  the  river  is  concerned. 

The  removal  of  suspended  matter  from  sewage  by  mechanical  means  is 
accomplished  by  screening  and  plain  sedimentation  in  basins  of  suitable  form 
and  mineral  substance  is  washed  into  the  sewers  from  the  streets  and  roofs, 
and  magnitude.  This  master  varies  considerably  in  amount  both  in  different 
hours  of  the  day  and  on  different  days  of  the  week,  and  also  with  the  state 
of  the  weather.  In  the  early  part  of  a  rainstorm,  a  large  quantity  of  earthy 
and  the  increased  flow  also  scours  out  deposits  which  may  have  accumulated 
in  the  sewers  themselves ;  but  after  a  short  time  the  water  rapidly  becomes 
clearer.  Provision  is  therefore  made  in  all  sewage  purification  works  to 
receive  from  2  to  4  times  the  dry-weather  flow,  the  remainder  of  the  liquid 
being  allowed  to  escape  at  storm-water  outlets. 

On  arriving  at  the  works,  the  sewage  should  flow  through  a  grating  or 
rack  on  which  the  coarse  floating  matter  is  retained,  and  then  through  a 
relatively  wide  and  deep  chamber  in  which  the  heavier  mineral  matter  is 
deposited.  It  passes  next  through  one  or  more  screens  with  small  meshes 
to  extract  all  but  the  finely  comminuted  suspended  matter,  and  then  flows  into 
a  series  of  large  tanks  in  which  most  of  the  remaining  suspended  matter  set¬ 
tles  slowly.  In  these  tanks  its  motion  is  generally  very  slow,  the  mean 
velocity  usually  being  from  8  to  12  inches  per  minute,  and  the  length  of  the 
tank  being  such  as  to  make  the  time  of  passage  from  2  to  3  hours.  The 
sewage  then  flows  continuously  in  a  thin  sheet  over  the  end  wall  of  the  tank 
into  an  outlet  channel  which  conveys  it  to  the  river  or  other  outfall. 

Much  attention  has  recently  been  given  to  the  details  of  clarification  pro¬ 
duced  by  sedimentation  or  precipitation  and  the  results  thereby  accomplished. 
At  Columbus,  O.,  experimental  tanks  40  ft.  long,  8  ft.  wide  and  8  ft.  deep  were 
used  in  1905,  and  about  two-thirds  of  the  total  suspended  matter,  including 
more  than  one-half  of  the  organic  matter  therein,  was  removed  by  plain 
■subsidence;  while  by  precipitation  with  aluminum  sulphate  about  three- 
fourths  of  the  total  suspended  matter,  including  80  per  cent,  of  the  organic 
matter  therein,  was  removed.  At  Worcester,  Mass.,  where  in  1905  an  average 
daily  flow  of  10,110,000  gallons  of  sewage  was  precipitated  with  lime  in  a 
series  of  large  masonry  tanks  having  an  aggregate  capacity  of  5,500,000  gal¬ 
lons,  85.8  per  cent,  of  the  total  suspended  matter  and  51.5  per  cent,  of  the 
total  organic  matter  were  removed ;  and  similarly,  at  Providence,  R.  I.,  where 
in  1904  an  average  daily  flow  of  20,000,000  gallons  of  sewage  was  precipitated 
with  lime  and  copperas  in  like  manner,  82.7  per  cent,  of  the  total  suspended 


19 


matter  and  49.4  per  cent,  of  the  total  organic  matter  were  removed.  These 
two  works  are  the  largest  of  their  kind  in  this  country. 

In  Great  Britain  there  are  many  sewage  works  of  greater  magnitude 
than  these  at  Worcester  and  Providence,  and  which  accomplish  the  same 
results.  Plain  sedimentation  without  the  use  of  chemicals,  however,  is  little 
practised,  owing  to  the  relative  smallness  of  the  streams  and  the  constant 
necessity  of  removing  the  greatest  practicable  quantity  of  organic  matter 
from  the  sewage.  Although  several  biological  processes  of  treatment  have 
organic  matter  has  been  considerably  overrated.  It  is  therefore  very  probable 
been  extensively  exploited  there  during  the  past  twelve  years,  it  has  now  come 
to  be  recognized  that  the  settling  of  the  suspended  matter  by  gravity  in  suitable 
economical  point  of  view  the  efficiency  of  bacterial  action  upon  the  solid 
tanks  is  the  essential  preparatory  feature,  and  that  from  a  practical  and 
that  the  removal  of  the  suspended  matter  in  sewage  by  improved  mechanical' 
and  sedimentation  processes  will  become  an  important  factor  in  future  methods 
of  purification. 

In  Germany  this  subject  has  recently  been  studied  very  closely,  and 
elaborate  experiments  with  settling  tanks  of  full  size  have  been  made  at 
Cologne,  Hanover,  Frankfort  and  other  cities,  in  addition  to  the  highly 
scientific  work  which  has  been  done  during  the  past  ten  years  in  laboratories 
with  small  tanks  like  those  used  at  Columbus.  The  object  of  these  investiga¬ 
tions  was  to  determine  by  practical  demonstrations  whether  the  use  of 
chemicals  for  precipitating  the  suspended  solids  could  not  safely  be  omitted, 
thereby  saving  a  large  percentage  of  the  cost  of  treating  the  sewage  before- 
discharging  it  into  the  rivers ;  and  the  results  proved  to  be  so  satisfactory 
that  wherever  the  stream  was  of  sufficient  magnitude  to  insure  adequate 
dilution,  the  governmental  conditions  respecting  the  use  of  chemicals  were 
withdrawn,  and  permission  was  given  to  clarify  the  sewage  by  screening  and 
plain  sedimentation.  It  is,  however,  proper  to  state  that  while  no  limit  was 
named  in  these  cases,  the  minimum  flow  of  the  stream  always  afforded  a 
dilution  of  more  than  20  times  the  volume  of  sewage  effluent. 

At  Cologne,  the  large  experimental  tank  was  148  feet  long,  26  feet 
wide  and  had  an  average  depth  of  6.5  feet.  The  population  connected  with  the 
sewerage  system  in  1901  was  348,000,  and  the  average  quantity  of  sewage 
per  capita  daily  was  160  liters  or  42.25  gallons,  containing  48.5  grams  or  3.14 
ounces  of  dried  suspended  matter,  and  142.7  grams  or  9.25  ounces  of  dried 
dissolved  matter.  The  total  amount  of  dry  solid  matter  in  the  sewage  was 
thus  191.2  grams  or  12.39  ounces  per  capita  daily,  of  which  71.1  grams  or 
4.61  ounces  were  organic  or  volatile  at  low  red  heat;  and  of  this  latter  2.23' 
ounces  were  suspended  and  2.38  ounces  dissolved.  The  sewage  thus  con¬ 
tained  31  per  cent,  more  organic  matter  per  capita  daily  than  the  quantity 
(3.53  ounces)  assumed  for  Rochester,  which  is  probably  excessive  for  Ameri¬ 
can  cities.  The  experiments  were  made  with  mean  velocities  of  flow  through 
the  tank  of  9.45,  47.3  and  94.5  inches  per  minute ;  and  it  was  found  from 
hundreds  of  accurate  analyses  that  with  a  velocity  of  9.45  inches  per  minute, 
70.9  per  cent,  of  the  suspended  and  9.1  per  cent,  of  the  dissolved  organic 
matter  were  removed,  while  with  a  velocity  of  47.3  inches  per  minute  the 
removal  was  respectively  68.6  and  3.6  per  cent.,  and  with  94.5  inches  it  was 
respectively  59.3  and  2.7  per  cent,  on  the  average.  Percentages  of  removal  of 
mineral  matter  are  here  omitted  as  being  of  no  significance  in  the  present 
case. 


20 


At  Cassel,  with  tanks  similar  to  that  at  Cologne,  and  with  velocities 
varying  from  5  to  24  inches  per  minute,  77.5  per  cent,  of  the  organic  matter 
in  the  sewage  is  removed  by  plain  sedimentation.  At  Frankfort,  under  like 
conditions,  from  70  to  90  per  cent,  of  the  suspended  matter  is  removed,  and 
it  has  been  found  by  long  trials  that  little  improvement  in  the  efficiency  of  the 
tanks  was  gained  by  the  moderate  use  of  chemicals ;  hence  the  work  is  now 
done  exclusively  by  screening  and  plain  sedimentation.  Numerous  other 
instances  of  sewage  clarification  by  this  simple  process  might  be  cited,  but 
it  is  believed  that  the  foregoing  will  suffice  to  show  its  applicability  in  many 
■cases  where  a  high  degree  of  purity  for  the  effluent  is  unnecessary. 

It  must  be  remembered,  however,  that  the  choice  between  plain  sediment¬ 
ation  and  chemical  precipitation  will  be  governed  in  a  large  degree  by  the 
character  of  the  sewage,  the  trade  wastes  it  contains  and  its  odor.  If  the 
latter  is  very  offensive,  and  cannot  be  abated  by  maintaining  the  system  of 
sewers  in  a  comparatively  clean  condition  by  proper  flushing,  it  may  be  ex¬ 
pedient  to  effect  at  least  a  partial  deodorization  by  adding  some  suitable  chemi¬ 
cal  substance,  such  as  sulphate  of  iron,  sulphate  of  alumina,  or  chloride  of 
lime,  to  the  liquid  before  its  entrance  into  the  settling  tanks.  In  many  cases 
the  trouble  is  caused  by  the  decomposition  of  organic  sediment  in  sewers 

having  flat  grades,  as  it  is  found  that  the  odor  disappears  after  the  flushing 

produced  by  a  heavy  rainfall,  while  in  others  it  is  due  to  certain  trade  refuse. 
The  most  common  precipitating  reagent  is  freshly-slaked  quicklime  on  account 
■of  its  cheapness,  but  it  is  often  supplemented  with  a  small  addition  of  copperas 

or  crude  alum.  Lime  is  used  at  the  rate  of  400  to  1,200  lbs.  per  million  gal¬ 

lons,  copperas  at  from  120  to  600  lbs.  and  crude  alum  or  compound  of  iron 
and  aluminum  sulphate  at  from  180  to  1,000  lbs.  The  quantity  used  varies 
with  the  character  of  the  sewage  and  trade  wastes,  and  the  rate  of  admixture 
is  generally  varied  at  different  hours  of  each  day. 

At  wholesale  the  present  prices  per  ton  of  these  substances  are  as 
follows: —  Lime  of  best  quality,  $5.85;  copperas,  $10.00;  crude  sulphate  of 
alumina,  $25.00.  To  indicate  the  cost  of  operating  such  chemical  precipit¬ 
ation  works  on  a  large  scale,  it  may  be  noted  that  at  Worcester,  Mass.,  where 
lime  alone  is  used,  the  cost  of  treatment  in  1905  was  $5.56  per  million  gallons, 
in  which  quantity  an  average  of  999  lbs.  of  lime  was  placed;  and  that  at 
Providence,  R.  I.,  where  683  lbs.  of  lime  and  58  lbs.  of  copperas  per  million 
gallons  were  used  in  1904,  the  cost  was  $3.42.  These  figures  are  for  the 
precipitation  expenses  alone,  and  in  addition  thereto  the  costs  of  disposing 
■of  the  sludge  were  respectively  $6.33  and  $2.57  per  millon  gallons  of  sewage; 
they  are  here  given  separately,  as  a  different  and  much  cheaper  method  of 
g-etting  rid  of  the  sludge  is  available  at  Rochester.  The  quantity  of  wet 
sludge,  containing  about  90  per  cent  water,  deposited  in  the  tanks  per  million 
gallons  of  sewage  was  4,190  gallons  (18.54  tons)  at  Worcester,  and  4,003 
gallons  (17.71  tons)  at  Providence. 


INTERCEPTION  OE  THE  PRINCIPAL  OUTLET  SEWERS. 

In  order  to  compare  the  cost  of  flushing  the  lower  river,  as  previously 
described,  with  the  costs  of  plain  sedimentation  and  chemical  treatment  of  the 


sewage  of  the  entire  city,  it  is  necessary  to  outline  a  method  by  which  the 
latter  process  can  be  accomplished  at  a  single  station,  as  in  the'  case  of 
Worcester  and  Providence.  A  study  of  the  sewerage  system  shows  that 
about  three  times  the  estimated  future  volume  of  the  dry-weather  flow  of  the 
principal  outlet  sewers  on  the  east  and  west  sides  of  the  river  can  be  collected 
at  a  point  about  800  ft.  north  of  the  intersection  of  Norton  Street  and  Hollen¬ 
beck  Street  in  the  following  manner : — 

By  a  tunnel  700  ft.  long  and  containing  an  18-inch  pipe  to  carry  the 
sewage,  from  the  intersection  of  Central  Avenue  and  North  Water  Street  to- 
the  tunnel  of  the  Front  Street  outlet  sewer  near  the  intersection  of  Central 
Avenue  and  Front  Street;  thence  by  a  20-inch  pipe  to  carry  the  combined  flow 
of  the  first-named  and  the  Front  Street  sewer  through  the  latter  tunnel  and 
its  shaft  to  the  flats  on  the  west  side  of  the  river  below  the  upper  falls,  a 
distance  of  800  ft. ;  thence  likewise  by  20-inch  pipe,  900  ft.  through  these  flats 
to  the  intersection  of  Factory  and  Falls  streets,  where  the  20-inch  pipe  would, 
be  joined  by  a  lateral  30-inch  pipe  450  ft.  long,  placed  in  a  new  shaft  and 
tunnel  for  diverting  the  sewage  of  the  Genesee  Valley  Canal  and  Platt  Street 
outlet  sewers  at  the  intersection  of  Factory  and  Mill  streets ;  thence  by  a 
36-inch  pipe  to  carry  the  combined  dry-weather  flow  of  the  aforesaid  three 
outlet  sewers,  northerly  through  Falls  Street  and  along  the  western  edge  of 
the  river  to  the  foot  of  Spencer  Street,  a  distance  of  2,400  ft. ;  here  the  36-inch 
pipe  would  be  joined  by  a  lateral  16-inch  pipe  250  ft.  long,  placed  in  the 
existing  shaft  and  tunnel  for  the  Spencer  Street  outlet  sewer;  thence  by  a 
42-inch  pipe  to  carry  the  combined  flow  of  the  said  four  outlet  sewers, 
northerly  to  the  foot  of  Avenue  B  on  the  east  side  of  the  river,  a  distance  of 
4,400  ft.,  of  which  700  ft.  is  in  tunnel  through  the  cliff  from  Spencer  to  the 
R.  W.  &  O.  R.  R.  bridge,  1,700  ft.  in  passing  through  the  flats  on  the  west 
side  and  the  remaining  2,000  ft.  in  crossing  the  river  and  passing  through  the 
flats  and  up  Brewer  Street. 

The  above  described  routes,  sizes  and  distances  must  be  considered  only 
as  approximations  until  accurate  surveys  and  gaugings  of  the  sewers  are  made. 
At  the  intersection  of  Avenue  B  and  Brewer  Street  the  surface  is  at  elevation 
+203.5,  and  the  top  of  the  42-inch  pipe  should  be  about  at  elevation +  174.0,  in 
order  to  obtain  the  necessary  fall  for  the  pipe  and  also  allow  ample  fall  for  a 
conduit  5,800  ft.  long  from  that  point  to  the  conduit  in  Hollenbeck  Street  for 
diverting  the  dry-weather  flow  from  the  East  Side  Trunk  Sewer  to  the  sewage 
purification  works,  the  elevation  of  the  top  of  the  latter  conduit  being  about 
+  161.0  at  the  place  of  junction,  800  ft.  north  of  Norton  Street.  To  avoid 
passing  through  private  property  a  route  for  this  conduit  would  be  through 
Avenue  B  to  St.  Paul  Street,  thence  through  the  latter  to  Strong  Street,  and 
thence  to  the  intersection  of  Strong  and  Hollenbeck  streets.  Owing  to  the 
great  depth  of  the  conduit  below  the  surface  in  the  first  half  of  this  route,  it 
will  be  expedient  to  construct  this  part  of  the  work  in  tunnel,  but  in  the 
remainder  of  the  distance  it  can  readily  be  done  in  open  excavation.  At  the 
intersection  of  Avenue  B  and  Brewer  Street,  the  conduit  would  be  5.0  ft.  in 
diameter  and  receive  directly  the  discharge  of  the  said  42-inch  pipe  and  the 
dry-weather  flow  of  the  Avenue  B  outlet  sewer ;  but  as  its  elevation  is  here 
18  ft.  above  that  of  the  invert  of  the  West  Side  Trunk  Sewer  at  the  top  of  the 
Hastings  Street  shaft,  the  normal  flow  of  this  sewer  can  be  diverted  into  it 
only  by  pumping  through  a  30-inch  pipe  about  1,200  ft.  long. 


22 


It  is  thus  shown  how  the  sewage  from  seven  of  the  eight  principal  outlet 
sewers  of  the  entire  city  can  be  permanently  diverted  from  the  river  and 
delivered  at  a  purification  plant  located  on  the  east  side  at  some  suitable 
point  north  of  the  city  line.  The  normal  flow  of  the  eighth  outlet  sewer  (for 
the  Lake  Avenue  district  north  of  Lake  View  Park)  might  also  be  diverted 
in  like  manner  by  pumping,  but  as  the  quantity  of  sewage  is  relatively  small, 
while  the  cost  of  diversion  will  be  unduly  large,  it  may  be  permitted  to  dis¬ 
charge  directly  into  the  river  for  many  years,  if  the  flow  of  all  the  other 
sewers  is  intercepted  and  purified  as  outlined  above.  It  should  be  further 
noted  that  the  sizes  and  grades  of  the  said  system  of  pipes  and  conduits  are 
adapted  to  carry  about  three  times  the  estimated  dry-weather  flow  of  these 
outlet  sewers  in  the  year  1925,  thus  providing  also  for  the  removal  and  treat¬ 
ment  of  the  storm  water  from  light  rainfalls,  or  the  first  flushing  of  the  sew¬ 
ers  by  heavier  showers. 

The  estimated  cost  of  this  work  from  the  intersection  of  Central  Avenue 
and  North  Water  Street  to  the  intersection  of  Strong  and  Hollenbeck  streets, 
including  800  ft.  of  conduit  4.0  ft.  in  diameter  from  the  East  Side  Trunk 
Sewer,  is  as  follows : — 

1.  700  lin.  ft.  tunnel  and  18-inch  pipe  under  river  and  races  from 

North  Water  Street  to  Front  Street  outlet  sewer  tunnel . $  20,000 

2.  Trimming  800  lin.  ft.  rock  walls  of  Front  Street  outlet  sewer 
tunnel  and  shaft,  to  receive  20-inch  pipe,  and  laying  said  pipe 
therein,  also  for  laying  900  lin.  ft.  additional  of  such  pipe  in  flats 

on  west  side  of  river  to  south  end  of  Falls  Street .  11,500 

3.  350  lin.  ft.  shaft  and  tunnel  and  100  ft.  open  trench  from  intersec¬ 
tion  of  Mill  and  Factory  streets  to  flats  near  south  end  of  Falls 
Street,  also  laying  450  lin.  ft.  of  30-inch  pipe  in  said  shaft,  tunnel 


and  trench  to  junction  with  aforesaid  20-inch  pipe .  13,700 

4.  2,400  lin.  ft.  trenching  and  laying  36-inch  pipe  through  Falls  Street  , 
and  lands  at  west  edge  of  river  to  foot  of  Spencer  Street  including 

200  ft.  of  tunnel .  26,700 

5.  Trimming  250  lin.  ft.  rock  walls  of  Spencer  Street  outlet  sewer 

tunnel  and  shaft,  to  receive  16-inch  pipe,  and  laying  said  pipe 
therein,  to  junction  with  36-inch  pipe .  3,000 


6.  700  lin.  ft.  tunnel,  400  lin.  ft.  river  crossing  and  3,300  lin.  ft. 

trenching  in  flats  on  west  and  east  sides  of  river  and  in  Brewer 


Street,  from  Spencer  Street  to  Avenue  B,  and  laying  4,400  lin.  ft. 
of  42-inch  pipe .  74,500 

7.  1,200  lin.  ft.  trenching  and  laying  30-inch  pipe  in  Hastings  Street, 

across  river  and  up  east  high  bank  of  river  from  shaft  of  West 
Side  Trunk  Sewer  to  foot  of  Avenue  B  on  east  side .  16,500 


8.  Pumping  station  and  steam  machinery  in  duplicate,  for  forcing 
dry-weather  flow  and  some  storm  water  from  West  Side  Trunk 
Sewer  through  said  30-inch  pipe  into  head  of  masonry  conduit 
at  foot  of  Brewer  Street .  25, '000 


23 


9.  Masonry  conduit  5.0  ft.  diameter,  constructed  for  2,850  ft.  in 
tunnel  and  for  2,950  ft.  in  open  trench,  through  Avenue  B,  St. 

Paul  Street  and  Strong  Street  to  Hollenbeck  Street .  108,500 

10.  800  lin.  ft.  masonry  conduit  4.0  ft.  diameter  in  Hollenbeck  Street 
from  Norton  Street  to  Strong  Street,  to  intercept  dry-weather 

flow  and  some  storm  water  from  East  Side  Trunk  Sewer....  13,600 


Total,  exclusive  of  contingencies . $313,000 

By  this  plan  of  interception  the  discharge  from  all  of  the  said  outlet 
sewers,  except  the  West  Side  Trunk  Sewer,  would  be  carried  away  by 
gravity,  while  that  from  the  latter  must  be  pumped  continuously  during  the 
low-water  season  against  a  head  of  at  least  21.0  ft.  On  referring  to  the 
table  giving  the  areas  and  prospective  populations  of  the  several  outlet 
sewer  districts,  it  will  be  found  that  the  West  Side  Trunk  Sewer  serves  an 
area  of  6,560  acres  or  10.25  square  miles,  of  which  1,047  acres  are  within  the 
present  city  limits,  and  that  the  estimated  future  population  thereof  is  35,000. 
At  the  rate  of  100  gallons  per  capita  daily,  the  dry-weather  flow  of  sewage 
from  this  district  will  eventually  become  5.43  cu.  ft.  per  second,  and  by  adding 
twice  as  much  storm-water  the  maximum  pumpage  would  be  about  16.5 
cu.  ft.  per  second.  With  centrifugal  pumps  having  an  efficiency  of  65  per 
cent.,  the  power  needed  for  pumping  thus  ranges  from  22  to  70  IHP.,  and 
as  the  district  is  so  large,  it  can  safely  be  assumed  that  an  average  of  at  least 
50  HP.  will  be  required  constantly  during  the  season. 

Owing  to  the  irregular  character  of  the  pumping  service,  it  is  probable 
that  the  work  can  be  done  more  economically  by  steam  than  by  electric 
power,  if  the  latter  is  purchased  of  a  private  corporation;  and  if  it  be  assumed 
that  the  pumping  will  embrace  an  average  of  120  days  per  year,  during 
which  coal  is  consumed  at  the  rate  of  5  lbs.  per  horse-power  per  hour,  that 
the  coal  will  cost  $3.25  per  ton,  and  that  three  crews  of  two  men  each  must 
be  employed  daily  for  5  months  per  year,  the  annual  operating  expenses  and 
maintenance  of  the  pumping  station,  exclusive  of  interest  and  other  fixed 
charges,  will  be  about  $4,000,  of  which  $1,200  is  for  coal.  It  will  be  shown 
subsequently  how  this  power  can  be  developed  at  very  small  cost  by  the 
clarified  sewage  effluent  of  the  purification  works,  and  be  transmitted 
electrically  to  the  pumping  station. 


COSTS  OF  MECHANICAL  AND  CHEMICAL  CLARIFICATION 
OF  THE  SEWAGE  OF  ROCHESTER. 

I 

From  the  intersection  of  Strong  and  Hollenbeck  streets,  the  intercepted 
sewage,  along  with  the  limited  quantity  of  storm-water  mentioned,  would 
be  conveyed  to  some  suitable  site  about  5,500  ft.  (more  or  less)  north  for 
treatment.  The  masonry  conduit  for  this  purpose  would  be  6.0  ft.  in  diameter, 
and  for  the  length  named  its  cost  would  be  $86,000.  To  avoid  litigation 
arising  from  existing  prejudices  against  the  establishment  of  sewage  purifi¬ 
cation  works  in  any  locality,  and  to  minimize  the  notice  of  any  possible  devel- 


24 


opment  of  disagreeable  odors  therefrom,  it  will  be  expedient  to  purchase  in 
the  outset  an  approximately  square  tract  of  land  containing  at  least  150  acres, 
and  to  locate  the  tanks  in  the  middle  thereof.  The  probable  cost  of  this 
quantity  of  land  is  not  known  at  present ;  but  as  not  more  than  10  acres  will 
be  required  for  the  sedimentation  tanks  and  accessory  works,  the  remainder 
-of  the  area  can  doubtless  be  rented  advantageously  for  agricultural  purposes, 
especially  if  coupled  with  the  promise  of  supplying  freely  all  the  sewage  that 
may  be  needed  thereon  for  fertilization  and  irrigation.  It  is  therefore  reason¬ 
able  to  expect  a  constant  yearly  revenue  from  this  source  which  will  be 
■equivalent  to  reducing  the  purchase  price  considerably. 

In  the  aforesaid  plan  for  flushing  the  lower  river,  a  population  of  275,000 
was  assumed  with  a  sewage  discharge  of  42.5  cu.  ft.  per  second.  The  same 
discharge  will  be  taken  for  estimating  the  costs  of  sedimentation  and  chemi¬ 
cal  treatment,  with  25  per  cent,  additional  quantity  for  storm  water,  as  the 
latter  appears  only  at  intervals  aggregating  not  more  than  360  hours  during 
120  days  of  summer  and  autumn.  Tank  capacity  need  be  provided  only  for 
the  dry-weather  flow  on  the  basis  of  21,000  cu.  ft.  per  tank  of  150  ft.  length, 
20  ft.  average  width,  and  7  ft.  average  depth,  with  2.4  hours’  time  of  passage, 
as  only  one  hour  will  suffice  when  the  sewage  is  mixed  with  storm  water. 
This  requires  about  18  tanks,  but  as  some  reserve  capacity  is  needed  for  use 
while  two  or  more  tanks  are  being  cleaned,  22  such  open  basins  will  be  assumed. 
The  average  cost  of  such  a  tank  with  its  accessory  channels  and  appliances 
for  receiving  and  *  removing  the  sewage,  sludge  and  clarified  effluent  is 
approximately  $5,200;  hence  for  22  tanks  about  $114,400  would  be  required. 

Before  entering  the  tanks  the  crude  sewage  would  pass  through  a 
■detritus  chamber  and  two  sets  of  screens  for  extracting  the  coarser  sus¬ 
pended  matter,  as  already  described.  This  apparatus  will  cost  about  $6,000. 
Provision  must  also  be  made  for  the  convenient  removal  of  the  sludge  or 
sediment  from  each  tank  by  means  of  a  suitable  conduit  and  pump,  and  its 
temporary  storage  in  a  large  covered  basin.  The  cost  of  the  latter,  along  with 
the  pump  well  and  sludge  conduit  connecting  the  two  series  of  tanks  will  be 
$7,500,  and  the  cost  of  a  combined  sludge  pumping  station  and  laboratory, 
with  its  proper  equipment  will  be  $10,000.  The  group  of  sedimentation  tanks 
can  be  located  at  a  point  about  2,500  ft.  easterly  of  the  top  of  the  high  bank 
of  the  lower  river,  and  the  effluent  would  be  carried  to  the  edge  of  the 
declivity  in  a  masonry  conduit  6.5  ft.  in  diameter  costing  $25,000,  and  thence 
down  the  high  bank  into  the  river  in  a  suitable  pipe. 

As  the  site  of  the  works  is  upward  of  140  ft.  above  the  river,  the  effluent 
from  the  tanks  will  at  once  become  available  for  the  development  of  a  large 
amount  of  water  power  at  the  edge  of  the  stream.  A  small  part  of  this 
power  can  easily  be  transmitted  electrically  to  the  sludge  pumping  station 
for  use  in  forcing  the  wet  sludge  through  a  6-inch  pipe  costing  $2,700  into 
suitably  covered  tank-barges  at  the  power  station  on  the  edge  of  the  river. 
The  remainder  of  the  power  so  generated  can  likewise  be  transmitted  elec¬ 
trically  two  miles  southerly  to  the  previously  mentioned  pumping  station 
near  the  mouth  of  the  West  Side  Trunk  Sewer,  where  it  would  take  the 
place  of  steam  power.  The  costs  of  the  constructions  involved  in  this  use 
of  the  effluent  and  production  of  electrical  power  for  said  pumping  purposes 
are  as  follows  :  For  two  36-inch  steel  outlet  pipes  down  the  high  bank  of 
the  river,  $5,300;  for  barge  dock  and  power  station  at  edge  of  river,  and  its 


25 


equipment  with  the  necessary  hydraulic  and  electrical  apparatus  in  duplicate- 
for  producing  100  HP.,  $17,700;  for  three  covered  tank-barges  for  carrying 
and  dumping  the  wet  sludge  far  out  in  the  lake,  $16,500;  for  2.5  miles  of 
electrical  transmission  line,  $3,500. 

The  sum  of  the  foregoing  items  of  cost  for  conduits,  pipes,  sedimenta¬ 
tion  and  sludge  tanks,  pumping  stations,  power-generating  apparatus  and 
sludge  barges,  from  the  intersection  of  Hollenbeck  and  Strong  streets  to  the 
barge  dock  at  the  edge  of  the  river,  is  $294,600.  To  this  should  be  added’ 
$29,400  for  general  contingent  expenses  of  construction,  such  as  engineering, 
inspection,  legal  services  and  unforeseen  expenses,  thus  making  the  cost  $324,- 
000,  exclusive  of  the  purchase  price  of  the  150  acres  of  land  deemed  necessary 
for  the  site  of  the  tanks  and  for  avoiding  complaints  from  the  owners  of  the 
adjacent  properties.  Should  it  be  found  that  said  land  can  be  acquired  for 
$76,000,  then  the  estimate  for  the  total  cost  of  the  plant  described  would  be- 
$400,000. 

With  respect  to  the  annual  operating  expenses  of  the  purification  works, 
it  will  be  assumed  that  the  cost  of  chemical  treatment  alone  per  million  gal¬ 
lons  of  sewage  is  $4.49,  which  is  the  average  of  the  costs  at  Worcester  and 
Providence ;  also  that  including  the  storm  water,  an  average  of  34,000,000' 
gallons  per  day  will  eventually  be  so  treated  for  120  days.  For  this  part  of 
the  work  the  ultimate  seasonal  expense  will  thus  be  $18,300,  to  which  must 
be  added  the  salaries  of  several  skilled  attendants  for  the  remainder  of  the 
year,  along  with  the  costs  of  maintaining  the  electrical  power  for  pumping 
the  sludge  and  of  getting  rid  of  the  same.  Including  the  pumping  station  of 
the  West  Side  Trunk  Sewer,  it  is  estimated  that  the  salaries  of  eight  such 
permanent  skilled  attendants  for  eight  months  will  amount  to  $5,200,  and  that 
on  the  basis  of  8  hours’  work  per  day  the  wages  for  four  months  of  the 
permanent  and  temporary  attendants  for  producing  the  power  and  pumping 
sewage  and  sludge  will  be  $5,900.  The  total  of  these  three  items  is  $29,400. 

When  the  population  becomes  275,000  and  the  average  daily  flow  of 
sewage  to  be  treated  is  34,000,000  gallons,  as  aforesaid,  wet  sludge  will  be 
produced  in  the  precipitation  tanks  at  the  average  rate  of  4,100  gallons  per 
million  gallons  of  sewage,  thus  making  the  daily  yield  139,400  gallons  or  603' 
tons.  It  is  proposed  to  pump  this  fresh  sludge  into  covered  tank-barges, 
at  the  said  electrical  power  station  at  the  edge  of  the  river,  and  then  to  tow 

them  8  or  10  miles  out  in  the  lake,  where  the  contents  would  be  quickly  dis¬ 
charged  by  merely  opening  a  few  large  valves  in  the  bottom  of  each  vessel. 

Such  discharge  would  always  be  made  at  a  point  sufficiently  far  from  shore- 

to  prevent  any  of  the  matter  from  being  carried  back  by  wind  or  waves. 
In  this  manner  the  ultimate  daily  product  of  wet  sludge  can  easily  be 
removed  within  a  period  of  8  or  10  hours  at  a  cost  of  not  more  than  $28.00* 
per  day,  embracing  rental  of  tug-boat  and  wages  of  barge  crew;  hence  for 
the  stated  season  of  120  days,  the  cost  of  getting  rid  of  the  sludge  will  be- 
about  $3,400. 

The  total  yearly  expense  of  operating  the  said  chemical  purification  plant 
will  thus  be  $32,800  when  the  population  and  quantity  of  sewage  treated' 
reaches  the  limits  named,  but  previous  to  that  time  it  will  be  proportionally 
less.  It  may  also  be  stated  that  the  average  of  the  costs  at  Worcester  and’ 
Providence  for  precipitation  alone  is  $2.68  for  chemicals  and  $1.81  for  labor 
per  million  gallons  of  sewage  treated  at  the  works,  not  counting  what  is; 

26 


required  for  disposing  of  the  sludge.  On  the  basis  of  34,000,000  gallons- 
daily,  the  expense  for  lime  and  copperas  used  during  the  estimated  season 
of  120  days  would  thus  be  about  $10,900;  and  hence  if  it  should  be  found  by 
actual  experience  that  an  adequate  clarification  of  the  Rochester  sewage  can 
be  secured  by  plain  sedimentation  without  the  use  of  chemicals,  the  total 
yearly  cost  of  thus  treating  34  million  gallons  per  day  for  120  days  will  be- 
only  $21,900,  instead  of  $32,800. 


COMMENTS  ON  MECHANICAL  AND  CHEMICAL  CLARIFI¬ 
CATION  PROCESS. 

It  was  shown  in  a  previous  paragraph  that  by  removing  two-thirds  of  the- 
suspended  organic  matter  in  the  sewage,  or  the  greater  part  of  that  which- 
tends  to  cause  the  river  to  become  offensive,  the  partially  clarified  effluent 
from  1.87  times  as  many  persons  should  be  inoffensively  diluted  by  the  same 
quantity  of  relatively  clean  river  water  as  was  needed  for  adequately  diluting 
the  crude  sewage  of  the  original  population.  It  was  also  seen  that  the 
minimum  flow  of  the  Genesee  River  was  capable  of  producing  an  inoffensive 
dilution  of  the  sewage  of  about  180,000  people ;  hence  it  follows  that  even  if 
the  minimum  flow  of  the  stream  is  not  increased,  it  should  be  able  to  dilute 
inoffensively  the  effluent  from  a  proper  chemical  treatment  of  the  sewage  of 
about  336,000  people. 

It  may,  however,  be  urged  that  the  usual  chemical  treatment  of  sewage 
does  not  always  accomplish  the  removal  of  two-thirds  of  the  suspended 
organic  matter,  and  that  in  many  cases  not  more  than  one-half  of  this  matter 
is  so  removed.  Granting  that  such  is  the  fact,  it  follows  that  even  if  only 
one-half  of  the  suspended  organic  matter  is  removed  by  such  a  process,  the 
minimum  flow  of  the  river  should  still  be  able  to  dilute  inoffensively,  the  par¬ 
tially  clarified  sewage  from  1.54  times  as  many  people  as  in  the  year  1905, 
or  from  a  population  of  about  275,000,  which  has  been  set  as  a  limit  for 
present  consideration.  It  was  also  shown  that  equally  good  results  had  been 
accomplished  by  plain  sedimentation  of  the  sewage  in  the  precipitation  tanks 
without  the  addition  of  chemicals. 

In  view  of  these  conditions  and  the  successful  results  attained  at  Wor¬ 
cester  and  Providence,  as  well  as  in  many  foreign  cities,  the  relatively  inex¬ 
pensive  method  of  sewage  treatment  outlined  above  is  worthy  of  the  most 
careful  consideration.  It  should  also  be  borne  in  mind  that  the  process  ol 
clarification  is  the  first  step  that  must  be  taken  in  any  known  mode  of 
purifying  sewage  other  than  by  natural  agencies  in  a  large  body  of  water. 
The  objections  are  that  such  a  plant  is  always  an  undesirable  feature  in  the 
suburbs  of  a  large  city,  and  that  great  care  must  constantly  be  exercised  to- 
keep  it  from  becoming  offensive ;  also  that  the  addition  of  future  trade  wastes 
may  make  the  process  much  more  expensive. 

The  principal  difficulty  associated  with  sedimentation  and  precipitation 
processes  has  hitherto  been  the  economical  disposal  of  the  wet  sludge.  In 
most  cases  where  the  purification  of  sewage  has  been  found  necessary,  great 
bodie$  of  water  like  Lake  Ontario  or  the  ocean  have  not  been  available,  and 
hence  ingenuity  has  been  taxed  to  the  utmost  to  devise  means  for  getting  rid 

27 


-of  the  sludge  inoffensively  and  inexpensively.  After  unsatisfactory  experi¬ 
ences  with  various  other  methods,  the  plan  of  removing  most  of  the  water 
from  the  sludge  by  means  of  a  filter-press  was  developed,  and  it  is  now 
generally  adopted  in  localities  where  disposal  at  sea  is  not  feasible.  In  this 
process  the  liquid  is  usually  mixed  with  a  certain  quantity  of  lime  and  is  then 
forced  by  pumps  and  high  air-pressure  through  sheets  of  canvas  placed 
between  large, cast-iron  plates  which  are  arranged  in  a  suitable  frame.  Most 
of  the  water  is  thus  blown  out  while  the  solid  matter  is  retained  between  the 
plates  in  the  form  of  a  moist  cake,  which  can  readily  be  transported  by  wagon 
and  dumped  in  some  place  where  its  subsequent  decay  will  not  cause  offense. 

At  Worcester  and  Providence  the  sludge  is  treated  in  this  manner,  and 
the  resulting  product  is  dumped  on  low  lands  in  the  vicinity  of  the  purifica¬ 
tion  works.  As  mentioned  above,  the  costs  of  dealing  with  the  sludge  at 
these  two  places  are  respectively  $6.33  and  $2.57  per  million  gallons  of 
sewage ;  hence  it  will  be  seen  that  the  plan  outlined  above  for  getting  rid  of 
the  sludge  from  the  proposed  sedimentation  tanks  is  vastly  more  economical. 

If  the  farming  land  in  the  region  is  deficient  in  lime,  the  cakes  of  pressed 
sludge  may  be  used  advantageously  as  a  top-dressing,  and  it  may  be  expected 
that  in  this  way  a  considerable  quantity  of  the  material  will  be  carted 
away  by  farmers ;  but  as  the  demand  for  it  is  necessarily  limited,  both  as  to 
time  and  distance,  an  extensive  permanent  dumping  ground  must  usually 
be  acquired  in  the  neighborhood  of  all  large  works.  Low  or  marshy  land 
is  generally  selected  for  this  purpose,  the  cakes  being  conveyed  thereto  in 
tramway  cars  from  the  pressing  house;  and  if  the  daily  product  is  large,  the 
transportation  is  done  by  trolley  or  by  a  small  steam  locomotive.  It  will 
thus  be  recognized  that  the  disposal  of  the  sludge  from  large  precipitation 
plants  is  a  serious  and  expensive  matter  when  other  simpler  means,  such  as 
those  proposed  and  described  above,  are  not  applicable. 

As  to  the  propriety  of  dumping  the  fresh,  wet  sludge  into  the  lake  far 
from  shore,  it  may  be  remarked  that  little  can  justly  be  said  in  opposition  on 
account  of  its  great  depth  and  magnitude.  There  is  no  scruple  about  dis¬ 
charging  therein  the  crude  sewage  from  Buffalo,  Toronto  and  many  other 
smaller  communities  situated  on  its  shores  and  tributaries.  There  is  also  no 
essential  difference  in  composition  between  the  sludge  and  the  sewage,  except 
in  respect  to  dilution,  and  this  is  very  quickly  changed  after  the  tank-barge 
is  emptied.  This  method  of  disposal  has  been  practiced  by  London  since 
1888  and  by  Manchester  since  1897,  and  the  following  description  of  the 
results  near  the  mouth  of  the  Thames,  given  on  page  214  of  Dibdin’s  treatise 
on  the  “Purification  of  Sewage  and  Water,”  London,  1903,  may  be  of 
interest : 

“The  discharge  takes  place  on  the  Barrow  Deep,  commencing  at  a  point 
10  miles  east  of  the  Nore,  and  proceeding  thence  from  5  to  10  miles  down  that 
channel.  *  *  *  As  the  sludge  is  discharged  from  the  bottom  of  the  vessel, 
■some  10  ft.  under  water,  and  is  thus  agitated  by  the  action  of  the  twin  screws 
(of  the  tank  steamer  carrying  1,000  tons),  the  diffusion  of  the  sludge  in  the 
water  in  the  wake  of  the  vessel  is  very  complete,  so  much  so  that  when  there 
is  but  a  slight  ripple,  the  visible  effect  of  the  sludge  is  lost  after  a  few 
minutes.  The  sand  and  earthy  matters  soon  separate  by  subsidence,  and  the 
animal  and  vegetable  debris  is  rapidly  consumed  by  the  organic  life  in  the 
sea  water.  This  is  evidenced  by  the  fact  that,  although  over  20,000,000  tons 


28 


of  sludge  have  now  (1894)  been  deposited  in  this  part  of  the  estuary,  the 
most  careful  microscopical  examination  and  chemical  analysis  fail  to  detect 
more  than  the  merest  trace  of  the  mineral  portion  of  the  sludge,  either  ins 
dredgings  from  the  bottom  of  the  channels  or  on  the  surface  of  the  sand¬ 
banks,  which  are  now  as  clean  as  in  1888.” 

•  On  comparing  the  costs  of  sewer  interception  and  chemical  treatment 
with  the  corresponding  ones  for  flushing  the  river,  and  remembering  that 
plain  sedimentation  will  probably  be  sufficient  for  a  long  time,  it  will  be  seen- 
that  the  flushing  projects  are  much  more  expensive  under  the  same  conditions. 
Furthermore,  these  projects  are  comparatively  inelastic  from  a  financial  point 
of  view,  as  a  very  large  outlay  is  involved  in  the  outset  for  a  great  reservoir 
or  a  long  tunnel  in  anticipation  of  the  future  growth  of  population ;  whereas; 
in  the  case  of  the  proposed  purification  works,  the  payment  of  a  considerable 
portion  of  the  ultimate  cost  and  yearly  expense  can  be  deferred  until  made 
necessary  by  circumstances.  It  may  also  happen  that  certain  trade  wastes 
will  hereafter  be  produced  in  the  city,  which  will  require  a  much  larger 
dilution  for  the  crude  sewage  than  was  estimated  above,  but  which  may  be 
favorable  for  sedimentation  or  chemical  precipitation;  and  if  this  should! 
ever  occur,  the  flushing  apparatus  would  be  at  a  serious  disadvantage. 


AVAILABILITY  OF  CLARIFIED  SEWAGE  FOR  PRODUC¬ 
TION  OF  POWER  AND  IRRIGATION. 

✓ 

There  are,  however,  other  good  reasons  for  adopting  the  plan  of  clari¬ 
fying  the  sewage  which  has  been  outlined  above.  At  one  of  the  sites  still 
available  for  the  works,  and  which  was  pointed  out  to  the  City  Engineer,, 
the  fall  to  the  river  is  at  least  140  feet.  The  estimated  future  dry-weather 
flow  of  sewage  from  the  seven  principal  outlet  sewers  to  be  intercepted  as 
previously  described  is  26,600,000  gallons  per  day ;  and  as  the,  rate  at  which 
sewage  is  produced  is  usually  about  twice  as  great  during  the  day-time  as  at 
night,  this  daily  quantity  will  accordingly  be  equivalent  to  a  flow  of  approxi¬ 
mately  60  cu.  ft.  per  second  for  8  hours  and  30  cu.  ft.  per  second  for  16  hours 
of  the  day.  With  an  effective  head  of  140  ft.,  these  volumes  of  clarified 
sewage  will  yield  respectively  700  and  350  HP.  on  turbine  shafts  of  a  power 
station  at  the  edge  of  the  river,  about  one-half  mile  distant  from  the  precipita¬ 
tion  tanks. 

As  already  indicated,  this  power  can  be  transformed  into  electrical 
energy  and  transmitted  economically  to  any  desired  locality  a  few  miles 
distant  with  a  loss  of  not  more  than  20  per  cent.,  so  that  the  future  available 
power  in  dry  weather  at  such  point  will  be  at  least  560  H..  P.  during  the  day 
and  280  H.  P.  during  the  night.  These  quantities  may  safely  be  regarded  as 
minima,  since  the  sewers  will  doubtless  receive  an  appreciable  volume  of 
ground  water  by  infiltration.  Of  the  power  so  produced,  about  70  H.  P.  will 
be  required  for  the  aforesaid  pumping  station  of  the  West  Side  Trunk  Sewer, 
and  about  15  H.  P.  will  be  needed  for  pumping  sludge  and  electric  lighting 
at  the  purification  works,  so  that  at  least  475  H.  P.  during  the  day-time  and 
195  H.  P.  at  night  will  ultimately  become  available  for  other  purposes.  It 
must  also  be  remembered  that  with  duplicate  machinery  this  surplus  power 


29 


•will  be  constant  and  reliable  every  day  in  the  year,  and  is  therefore  of  the 
highest  market  value.  It  can  be  impaired  only  by  the  failure  of  the  city’s 
water  supply,  which  is  a  contingency  too  remote  for  serious  consideration. 

For  the  development  of  700  H.  P.  at  the  said  power  station  throughout 
the  year,  it  will  only  be  necessary  to  enlarge  the  building  and  power  apparatus 
previously  described,  and  to  make  permanent  the  employment  of  several  of 
the  otherwise  temporary  attendants  at  the  purification  works  and  West  Side 
Trunk  Sewer  pumping  station.  During  an  average  of  eight  months  in  the 
year  the  crude  sewage  would  thus  be  merely  screened  at  an  additional  yearly  cost 
of  $3,600,  and  the  constant  employment  of  the  various  attendants  at  the  three 
power  stations  for  the  same  period  would  involve  an  additional  expense  of 
$10,000.  The  cost  of  the  additional  power  plant  in  duplicate  will  not  exceed 
$50,000,  and  if  an  allowance  of  9  per  cent,  thereon  be  made  for  interest, 
maintenance  and  sinking  fund,  the  total  additional  yearly  cost  of  producing 
the  said  quantities  of  surplus  permanent  power  will  be  $18,100. 

Reckoning  that  the  surplus  of  475  H.  P.  in  the  day-time  continues  for 
only  8  hours,  while  that  of  195  H.  P.  at  night  continues  for  16  hours,  each  day 
in  the  year,  the  total  yearly  output  of  surplus  power  will  be  about  1,894,000 
kilo-watt  hours  of  electrical  energy.  This  should  have  a  wholesale  market 
value  to  the  city’s  lighting  and  traction  interests  of  at  least  1.25c.  per  kilo¬ 
watt  hour,  and  thus  produce  a  revenue  of  $23,675,  or  a  net  annual  profit  of 
$5,575,  which  could  be  applied  to  reducing  the  cost  of  operating  the  sewage 
purification  works  during  four  months  of  the  year.  It  may  be  added  that 
this  estimate  has  been  made  on  a  very  conservative  basis,  and  that  if  such  a 
market  for  all  the  surplus  power  produced  by  the  sewage  can  be  found,  both 
the  quantity  and  the  net  profit  will  be  considerably  increased  by  making  use 
of  the  intercepted  storm  water  which  is  carried  to  the  purification  works. 

Another  use  that  might  be  made  of  the  clarified  sewage  is  for  cheaply 
irrigating  an  area  of  from  10,000  to  15,000  acres  of  sandy  farming  land  in 
the  township  of  Irondequoit.  By  this  means  the  productiveness  of  the  land  will 
be  greatly  increased,  and  it  may  safely  be  presumed  that  after  a  demonstra¬ 
tion  has  been  given  on  the  land  at  the  precipitation  tanks,  the  surrounding 
farm-owners  will  unite  in  providing  a  distributing  system  at  their  own 
expense.  Probably  preference  will  be  given  to  the  clarified  liquid,  so  that  no 
saving  in  tank  capacity  or  sludge  disposal  will  occur  from  such  use ;  but 
the  lower  river  will  then  be  relieved  of  the  duty  of  diluting  the  quantity  of 
•clarified  sewage  so  diverted. 

The  manner  in  which  this  can  be  accomplished  is  as  follows : —  With  a 
Read  of  140  ft.,  one-third  of  the  effluent  from  the  tanks  will  produce  suffic¬ 
ient  power  to  pump  the  remaining  two-thirds  of  either  the  screened  or  clari¬ 
fied  sewage  to  an  elevation  in  a  stand-pipe  high  enough  to  allow  it  to  be 
distributed  by  gravity  through  a  system  of  pipes  and  open  ditches  in  the 
territory  mentioned.  The  cost  of  the  necessary  additional  power  plant,  centrif¬ 
ugal  pumps  and  stand-pipe  would  not  exceed  $25,000,  and  there  would  be  no 
increase  in  the  annual  operating  expenses,  as  the  irrigation  service  would  be 
performed  and  required  only  during  the  four  months  of  the  dry  season  of 
each  year.  It  is,  however,  not  expedient  for  the  city  to  construct  and  operate 
the  distributing  system,  and  therefore  this  part  of  the  work  would  have  to 
be  done  by  an  organization  of  the  land-owners,  under  positive  agreement  to 
take  a  definite  quantity  of  liquid  each  week  during  the  season. 


30 


Of  the  comparative  merits  of  these  two  plans  for  utilizing  the  sewage, 
little  further  need  be  said.  Both  involve  co-operation  with  private  interests, 
and  unless  the  strongest  assurance  is  given  that  the  agreements  will  be  faith¬ 
fully  observed  for  a  long  term  of  years,  the  initial  outlay  on  the  part  of  the 
city  for  the  necessary  additional  plant  cannot  be  justified. 


DISCHARGE  OF  THE  CRUDE  SEWAGE  DIRECTLY  INTO 

LAKE  ONTARIO. 

The  conditions  under  which  the  crude  sewage  of  the  city  can  be  discharg¬ 
ed  directly  into  Lake  Ontario  will  next  .be  considered.  On  the  west  side  of 
the  river,  the  shortest  distance  to  the  lake,  from  a  point  in  Lake  Avenue 
■opposite  Norton  Street,  is  about  5.22  miles,  while  on  the  east  side  it  is  4.43 
miles  in  a  direct  line  from  the  intersection  of  Norton  and  Hollenbeck  streets. 
On  referring  to  the  map  of  the  lake,  it  will  be  seen  that  from  Manitou  Point 
to  Irondequoit  Bay  the  shore  has  a  southeasterly  direction,  and  then  turns 
abruptly  to  the  northeast  for  a  distance  of  8  miles  to  a  point  near  the  east 
line  of  Monroe  County,  thus  forming  an  extensive  indentation.  The  distance 
in  a  straight  line  between  the  two  points  named  is  19  miles,  and  from  this 
line  to  the  bar  between  the  lake  and  the  bay  the  distance  is  5  miles,  while  at 
the  mouth  of  the  river  it  is  4  miles.  Near  the  shore  the  water  is  quite 
■shallow,  but  it  gradually  becomes  deeper  until  a  depth  of  35  feet  is  reached 
at  a  distance  of  5,000  ft.,  and  beyond  that  distance  the  depth  increases  to  a 
maximum  about  700  feet.  The  width  of  the  lake  in  this  locality  is  about  46 
miles,  and  the  prevalent  winds  are  from  the  northwest. 

At  the  mouth  of  the  river  the  water  is  generally  shallower  than  else¬ 
where,  and  a  channel  for  navigation  is  maintained  by  two  parallel  jetties 
about  2,600  feet  long.  For  a  distance  of  two  miles  on  each  side  of  the  river, 
the  shore  of  the  lake  is  thickly  lined  with  cottages  and  summer  resorts,  and 
similar  settlements  are  in  process  of  development  at  various  other  places 
between  Manitou  and  Nine-Mile  points.  It  is  therefore  very  apparent  that 
the  delivery  of  large  quantities  of  crude  sewage  at  or  near  the  shore  would 
not  be  tolerated,  and  that  if  it  were  done  at  all,  the  foul  liquid  would  have 
to  be  conveyed  in  a  pipe  not  less  than  5,000  ft.  long  into  water  at  least  35  ft. 
in  depth.  It  is  also  highly  probable  that  unless  the  pipe  were  made  much 
longer  than  5,000  ft.,  this  mode  of  disposing  of  the  sewage  would  soon  give 
rise  to  serious  complaints,  with  the  result  that  some  process  of  purification 
would  have  to  be  established  under  far  less  favorable  conditions  for  economy 
of  operation  than  those  existing  near  the  northern  boundary  of  the  city. 

Owing  to  these  circumstances,  as  well  as  to  the  long  distance  from  Norton 
Street  to  the  lake,  the  exclusion  of  practically  all  the  sewage  from  the  river 
would  make  it  expedient  to  collect  the  dry-weather  flow  from  various  outlet 
sewers,  as  previously  indicated,  into  a  single  conduit  on  the  east  side  of  the 
river;  and  as  such  an  undertaking  would  be  expected  to  remain  adequate 
for  at  least  20  years,  at  the  end  of  which  time  the  population  will  probably 
be  not  less  than  275,000,  it  would  be  prudent  to  make  the  discharging  capacity 
of  such  conduit  about  150  cu.  ft.  per  second.  This  quantity  represents  the 
estimated  volume  of  sewage  at  the  rate  of  100  gallons  per  head  daily,  with 
the  addition  of  an  average  of  2.5  times  as  much  storm-water. 


31 


In  my  former  report  several  routes  for  such  an  outlet  sewer  were  con¬ 
sidered.  The  most  expedient  one  is  from  the  intersection  of  Strong  and 
Hollenbeck  streets  to  a  point  on  the  shore  about  1.5  miles  east  of  Summer¬ 
ville.  It  has  a  length  of  about  23,000  ft.,  or  4.36  miles,  and  the  grades  of 
the  conduit  vary  from  1  in  300  to  1  in  1,000  for  the  greater  part  of  the  way. 
With  a  discharge  of  150  cu.  ft.  per  second,  the  diameter  would  thus  range 
from  5.5  to  7.0  ft. ;  and  with  present  prices  of  labor  and  materials,  the  average 
cost  would  be  about  $14.00  per  lineal  foot,  including  a  moderate  allowance 
for  right  of  way  and  land  damages  where  the  location  is  in  fields.  At  this  price 
the  cost  of  the  masonry  conduit  would  be  $322,000,  to  which  $3,000  should  be 
added  for  manholes. 

Near  the  shore  the  land  is  approximately  50  ft.  above  the  ordinary  surface 
of  the  water,  and  most  of  this  height  must  be  utilized  to  overcome  the  fric¬ 
tional  resistances  in  the  terminal  outlet  conduit  to  a  point  as  far  out  in  the 
lake  as  practicable.  To  avoid  suits  for  damages  caused  by  pollution,  this 
point  should  be  located  at  least  7,000  ft.  from  shore,  where  the  depth  of 
the  water  is  about  45  ft.,  in  order  that  thorough  sedimentation  of  the  sus¬ 
pended  matter  and  diffusion  of  the  dissolved  matter  may  take  place. 

Deep  borings  for  wells  in  this  locality  indicate  that  the  subsoil  consists 
of  fine  silt  interspersed  with  veins  or  strata  of  quicksand,  and  consequently 
tunneling  operations  under  the  bed  of  the  lake  will  be  extremely  expensive 
and  hazardous.  It  therefore  follows  that  the  sewage  should  preferably  be 
conveyed  from  the  shore  in  a  submerged  pipe,  laid  in  a  dredged  trench  so  as 
not  to  cause  interference  with  navigation  and  be  protected  from  injury  and 
displacement  by  wave  action,  dragging  anchors  and  wrecks. 

The  surface  of  the  lake,  moreover,  is  subject  to  annual  and  seasonal  fluctu¬ 
ations  of  elevation,  due  to  excess  or  deficiency  of  rainfall,  and  also  to  the 
action  of  strong  winds.  Since  1860,  the  extreme  seasonal  variation  has  been 
5.5  ft.  from  the  maximum  in  the  summer  of  1870  to  the  minimum  in  the 
winter  of  1895-96,  and  a  temporary  rise  of  two  feet  or  more  may  be  caused' 
by  northerly  gales.  In  1904  there  was  a  seasonal  rise  of  3  ft.  from  January  to 
July,  which  is  the  largest  that  has  been  observed  since  1892.  In  computing 
the  size  of  the  outlet  pipe,  allowance  must  therefore  be  made  for  a  high 
elevation  of  the  surface  of  the  lake,  as  well  as  for  a  length  of  about  600  feet 
from  the  shore  inland;  and  it  will  accordingly  be  assumed  that  the  pipe  is- 
7,600  feet  long,  with  an  effective  head  of  40  feet,  and  a  discharging  capacity 
of  150  cu.  ft.  per  second. 

For  a  riveted  steel  pipe  these  conditions  require  a  diameter  of  5.0  feet. 
Of  the  total  length,  about  6,600  feet  would  be  provided  with  either  flexible  or 
flanged  joints  at  intervals  of  110  ft.,  and  be  laid  in  the  dredged  trench  either 
from  scows  or  with  the  aid  of  divers.  At  its  end  the  pipe  would  be  enclosed 
in  a  submerged  crib  and  equipped  with  three  34"  outlets,  to  distribute  the 
sewage  in  different  directions.  The  remaining  1,000  ft.  of  the  pipe  at  the 
shore  would  be  laid  in  the  usual  manner  in  an  open  trench,  of  which  three 
or  four  hundred  feet  would  be  protected  by  a  suitable  coffer-dam.  The 
estimated  cost  of  this  outlet  pipe  with  its  accessories  is  $195,000,  and  if  that 
of  the  23,000  feet  of  masonry  conduit  from  Strong  Street  to  the  lake  shore 
is  added,  along  with  10  per  cent  for  contingencies,  the  sum  will  be  $572,000. 

This  estimate  contains  no  provision  for  a  considerable  area  of  land 
near  the  shore  of  the  lake  for  settling  tanks  or  other  partial  purification 


32 


"works  that  may  become  necessary  in  the  future,  and  it.  will  therefore  be 
prudent  to  anticipate  that  such  works  will  ultimately  be  required.  For  this 
purpose  at  least  100  acres  should  be  acquired  in  order  to  avoid  complaints 
from  offensive  odors ;  and  as  the  land  can  doubtless  be  obtained  now  on 
more  favorable  terms  than  hereafter,  its  cost  should  properly  be  included  in 
the  estimate.  The  undersigned  has  no  definite  knowledge  of  the  market 
value  of  the  land  in  question,  but  will  assume  that  such  a  tract  can  be  pur¬ 
chased  for  about  $38,000.  It  will  also  be  assumed  that  an  expensive  purifi¬ 
cation  of  the  sewage  at  the  lake  shore  will  not  become  necessary  within 
the  next  30  years,  so  that  the  total  cost  of  this  method  of  disposal  may  be 
taken  at  $610,000,  exclusive  of  the  system  of  intercepting  pipes  and  conduits 
from  the  upper  falls  to  the  intersection  of  Strong  and  Hollenbeck  streets. 

In  view  of  the  existing  cottages  and  summer  resorts  on  the  shore  of  the 
lake,  it  will  be  reasonable  to  consider  that  the  crude  sewage  must  at  least 
be  freed  from  the  coarse  matter  carried  in  suspension  before  it  can  be  dis¬ 
charged  at  a  distance  of  even  7,000  feet  from  shore.  This  extraction  of  coarse 
solids  must  be  carried  on  continuously  throughout  the  year  in  order  to  pre¬ 
vent  the  beach  from  becoming  offensive,  and  hence  the  plan  entails  a  constant 
operating  expense  for  attendance  at  the  screens  and  disposing  of  the  matter 
"by  burial  or  burning.  As  the  work  must  be  done  at  all  hours  of  the  day, 
three  crews  of  attendants  will  be  required,  and  a  very  moderate  estimate 
•of  the  annual  cost  for  labor  and  maintenance  of  the  screening  plant  is  $8,000. 

By  this  plan,  however,  no  power  can  be  developed  with  the  sewage,  and 
it  will  become  necessary  to  operate  the  pumping  station  of  the  West  Side 
Trunk  Sewer  by  steam,  or  its  equivalent.  If  the  station  is  equipped  with 
steam  engines  and  boilers,  the  operating  expenses  for  four  months  per  year 
will  be  $4,000,  as  previously  stated.  This  annual  sum  must  obviously  be 
taken  into  account  in  comparing  the  costs  of  discharging  the  sewage  into 
the  lake  with  those  of  chemical  or  sedimentation  treatment  and  the  devel¬ 
opment  of  electrical  power,  as  in  the  operating  expenses  for  the  latter  the 
cost  of  all  necessary  attendance  for  the  said  pumping  station  was  included. 
The  yearly  charge  for  the  operation  of  the  lake  plan,  including  said  station, 
will  thus  be  at  least  $12,000. 

The  arguments  in  favor  of  this  plan  of  sewage  disposal  are  as  follows  : — 
In  passing  through  the  long  submerged  outlet  pipe,  the  sewage  will  acquire 
nearly  the  same  temperature  as  the  water  of  the  lake  at  the  depth  of  45  ft. 
According  to  the  observations  made  by  Mr.  George  H.  Benzenberg,  C.  E., 
in  connection  with  the  submerged  60-inch  intake  pipes  from  Lake  Michigan 
for  the  water  supply  of  Milwaukee,  the  temperature  of  the  lake  water  at 
the  depth  of  60  ft.  ranges  throughout  the  year  from  37°  to  42°  F.,  thus  varying 
but  little  from  that  (39.2°  F.)  at.  which  fresh  water  attains  its  maximum 
density.  In  Lake  Erie,  near  Cleveland,  Mr.  George  G.  Whipple,  C.  E., 
found  that  during  the  spring  of  1904  the  temperature  of  the  water  was 
substantially  the  same  at  all  depths,  being  about  36°  F.,  while  during  the 
summer  of  that  year  it  rose  to  70°  F.  at  a  depth  of  45  ft.  and  remained 
practically  uniform,  but  that  between  45  ft.  and  55  ft.  it  fell  rapidly  and  was 
50°  F.  at  a  depth  of  60  ft.  Definite  observations  of  the  temperature  at  dif¬ 
ferent  depths  in  Lake  Ontario  at  Charlotte  are  not  available,  but  it  is  well 
known  to  divers  that  in  summer  the  water  at  a  depth  of  40  ft.  is  much  colder 
than  70°  F.,  and  is  probably  not  more  than  55°  F. 


33 


At  this  depth  and  summer  temperature,  there  will  be  no  tendency  for 
the  screened  sewage  to  rise  to  the  surface  of  the  lake,  and  a  rapid  sedimenta¬ 
tion  of  the  suspended  matter  will  take  place.  Putrefactive  processes  will' 
also  be  greatly  retarded  and  the  dissolved  organic  matter  will  be  thoroughly 
diffused  in  a  vast  volume  of  water  by  the  action  of  the  winds  and  currents. 
No  disturbance  of  the  accumulating  sediment  will  usually  occur  by  wave 
action  until  it  rises  to  within  30  ft.  of  the  surface,  when  the  upper  layer  of 
the  mass  will  be  carried  away  to  settle  in  another  place  where  the  water 
is  deeper.  In  the  course  of  time  portions  of  the  organic  matter  in  the 
deposit  will  disappear  entirely  by  natural  microbic  agencies,  and  if  the- 
coarse  mineral  matter  is  abstracted  from  the  sewage  by  means  of  a  relatively 
small  detritus  tank  before  it  enters  the  outlet  pipe,  the  tendency  to  form  a 
sand  bank  at  the  point  of  discharge  will  be  minimized.  The  worst  that  can 
happen  in  this  respect  will  be  the  necessity  for  some  dredging  in  the  locality 
at  intervals  of  a  few  years. 

A  serious  pollution  of  the  lake  water  is  not  to  be  feared,  as  it  has  not 
occurred  in  the  past  from  the  sewage  of  all  the  cities  on  the  great  lakes. 
The  Niagara  River  delivers  into  the  western  end  of  the  lake  more  than 
220,000  cu.  ft.  of  highly  oxygenated  water  every  second,  and  the  St.  Lawrence 
River  carries  this  away  at  the  eastern  end,  so  that  a  slow  but  steady  current 
to  the  east  is  constantly  in  operation.  It  has  also  been  found  by  long  experi¬ 
ence  with  the  water  supplies  of  the  cities  on  the  Great  Lakes  that  when  the 
intake  is  located  twro  or  three  miles  above  the  mouth  of  a  sewage-polluted’ 
river,  no  contamination  of  the  water  ensues.  This  matter  accordingly 
becomes  of  significance  only  if  the  city  should  grow  to  such  magnitude  as  tO' 
render  it  necessary  to  resort  to  the  lake  for  a  future  additional  water  supply; 
and  in  this  event  the  intake  would  doubtless  be  located  west  of  Manitou  Point, 
which  is  about  9  miles  west  or  above  the  mouth  of  the  said  outlet  pipe. 

Another  strong  reason  for  adopting  the  plan  in  preference  to  chemical 
treatment  of  the  sewage  near  the  northern  boundary  of  the  city,  is  its 
simplicity  of  operation  and  the  relatively  small  annual  operating  expenses' 
which  it  entails.  The  number  of  permanent  and  temporary  employees  is 
small,  and  the  work  is  not  associated  with  dangers  of  any  kind.  Futhermore,. 
the  topography  of  the  region  along  the  shore  from  Windsor  Beach  to- 
Irondequoit  Bay,  and  extending  for  nearly  two  miles  inland,  is  so  broken  by 
numerous  deep  gullies  that  it  is  not  adapted  for  even  village  development; 
and  hence  it  cannot  be  alleged  that  an  impairment  of  the  prospective  value 
of  the  land  for  residence  purposes  will  result,  even  if  future  conditions  should 
compel  the  city  to  subject  the  sewage  to  a  sedimentation  process  before  dis¬ 
charging  it  into  the  lake.  The  project  is  therefore  free  in  large  measure  from 
the  objection  to  the  establishment  of  a  purification  plant  near  the  present  city 
limits. 

On  the  other  hand  it  may  be  argued  that  in  consequence  of  future 
legislation  or  litigation,  the  sewage  will  eventually  have  to  undergo- 
further  treatment  before  flowing  into  the  outlet  pipe.  In  that  case,  the  same 
system  of  sedimentation  tanks  already  described  must  be  provided  and  oper¬ 
ated  as  a  preliminary  to  some  still  more  efficient  method  of  purification;  and 
as  the  land  near  the  shore  of  the  lake  is  not  adapted  to  sewage  irrigation  or 
filtration,  the  site  should  be  so  chosen  and  the  works  so  planned  as  to 
afford  ample  space  for  the  various  artificial  filter  beds  and  the  disposal  of  the- 


34 


sludge.  It  must  also  be  remembered  that  in  this  location  there  is  no  available 
fall  for  generating  water-power  with  the  sewage,  and  that  any  power  that  may 
be  needed  for  pumping  and  lighting  must  be  derived  from  steam.  These 
considerations,  coupled  with  the  manifest  necessity  of  constantly  operating 
the  plant,  will  make  it  clear  that  the  annual  expenses  of  treating  the  sewage 
will  be  considerably  greater  than  at  the  location  previously  indicated. 

In  the  latter  case  the  lower  river  with  its  large  channel,  its  length  of 
six  miles  and  its  usually  sluggish  current,  acts  as  a  vast  settling  tank  in  which 
the  dissolved  and  finely-divided  organic  matter,  along  with  the  sewage  bac¬ 
teria,  are  constantly  attacked  by  another  class  of  bacteria  and  organisms, 
and  are  soon  changed  into  harmless  chemical  compounds.  If  the  pollution 
is  restricted  to  proper  limits,  these  natural  agencies  are  fully  as  efficient  and 
reliable  as  any  artificial  device  for  refining  the  effluent  of  a  sedimentation  or 
precipitation  process,  so  that  the  river  becomes  a  highly  important  and 
valuable  adjunct  to  such  methods  of  sewage  purification.  It  practically  takes 
the  place  of  a  large  number  of  sprinkling  filters  or  contact  beds  with  their 
costly  accessories,  so  far  as  the  quality  of  the  water  at  Charlotte  is  con¬ 
cerned. 

It  must  also  be  remembered  that  it  is  utterly  impracticable  to  render  the 
water  potable  within  the  city  limits,  as  the  river  must  always  continue  to 
receive  the  storm  drainage  of  the  city,  along  with  that  of  the  remainder  of  its 
large  watershed;  and  if  it  is  relieved  during  the  season  of  low-water  of  the 
greater  part  of  the  offensive  suspended  matter  in  the  sewage,  as  above  out¬ 
lined,  it  will  certainly  be  able  to  deal  at  such  time  with  the  remainder.  As 
the  flow  increases,  a  larger  amount  of  pollution  will  be  permissible,  until  the 
river  finally  reaches  a  stage  at  which  experience  has  demonstrated  that  the 
whole  of  the  sewage  can  safely  be  admitted  without  treatment.  With  a 
precipitation  plant  located  near  the  present  northern  boundary  of  the  city,, 
the  aim  should  be  to  maintain  the  quality  of  the  water  at  the  mouth  of  the 
river  at  a  nearly  uniform  standard  of  relative  purity  throughout  the  year,  by 
taking  advantage  of  the  varying  rates  of  flow  and  the  natural  processes  of 
purification  just  indicated,  at  the  same  time  keeping  the  portion  of  the  stream 
above  its  mouth  in  such  condition  that  it  will  not  be  offensive  to  sight  and 
smell. 


OTHER  METHODS  OF  SEWAGE  TREATMENT. 

In  my  former  report,  and  also  in  the  foregoing,  reference  was  made  to> 
other  methods  of  purifying  sewage,  and  a  brief  consideration  of  such  will 
now  be  offered.  Concerning  irrigation  and  intermittent  filtration  of  sewage 
through  natural  porous  soil,  combined  with  profitable  agriculture,  it  can  be 
said  that  on  a  large  scale  this  method  involves  entirely  too  much  area  and 
skilled  labor  for  its  successful  practice  by  American  municipal  administra¬ 
tions,  and  that  satisfactory  results  can  be  expected  only  when  the  work  of 
distributing  the  sewage  is  performed  by  an  association  of  private  land- 
owners.  In  any  event,  conditions  of  weather  and  crops  may  often  occur, 
especially  in  the  cold  season,  when  an  independent  outlet  for  the  sewage 
becomes  necessary;  and  if  the  city  incurs  the  expense  for  the  latter,  it  will 

35 


generally  be  found  that  the  same  can  be  made  available  during  the  entire 
time  with  less  additional  cost  than  by  acquiring  and  cultivating  the  requisite 
area  of  farming  land.  This  remark  also  applies  to  the  case  of  intermittent 
filtration  through  natural  soil  without  cultivation. 

The  biological  or  bio-chemical  methods  of  purifying  sewage  that  have 
been  developed  within  the  past  ten  years  involve  four  distinct  procedures. 
The  first  is  the  removal  of  the  coarse  organic  and  mineral  solids  ;  the  second 
is  the  removal  of  most  of  the  fine  matter  in  suspension,  or  the  clarification 
of  the  liquid ;  the  third  is  the  oxidation  of  the  dissolved  organic  matter  to 
such  extent  as  to  render  the  liquid  non-putrescible  for  a  few  days  in  summer ; 
and  the  fourth  is  the  disposal  of  the  coarse  solids  and  fine  sludge.  By  the 
septic  tank,  a  relatively  small  part  of  the  suspended  organic  matter  becomes 
liquefied,  and  another  small  part  is  converted  into  gas  which  escapes  into  the 
atmosphere.  In  most  cases,  however,  a  very  considerable  portion  of  the 
suspended  organic  matter  remains  in  the  tank  in  the  form  of  scum  and 
sludge  which  must  be  removed  from  time  to  time.  The  liquid  effluent  is 
usually  turbid  and  offensive  in  odor,  and  when  it  is  sprayed  or  poured  in 
thin  films  over  a  mass  of  very  porous  material  like  screened  gravel  or  broken 
stone  for  the  purpose  of  oxidation,  the  odor  is  liberated  much  more  exten¬ 
sively  than  from  open  settling  tanks  containing  the  original  crude  sewage. 
In  this  way  a  nuisance  is  caused  from  large  works  which  depends  greatly 
on  the  weather,  the  character  of  the  sewage,  its  degree  of  septicity,  and  the 
efficiency  of  the  preparatory  process  of  clarification. 

In  the  septic  method  of  treatment,  the  sewage  remains  in  the  tank  from 
£  to  16  hours,  and  hence  a  much  larger  storage  capacity  is  required  than  for 
plain  sedimentation.  The  cost  of  the  plant  is  thereby  greatly  increased. 
Recent  experiments,  however,  have  shown  that  satisfactory  results  can  often 
be  attained  by  oxidizing  in  the  manner  indicated  above  the  effluent  from  sedi¬ 
mentation  tanks  after  only  two  or  three  hours,  but  this  seems  to  depend  on 
the  composition  of  the  sewage  and  the  degree  of  cleanliness  maintained  in  the 
entire  system  of  sewers.  If  the  pipes  and  conduits  are  not  kept  free  from 
•deposits,  septic  action  takes  place  therein,  and  the  difficulties  of  treatment  are 
at  once  augmented.  Certain  trade  wastes,  such  as  those  from  breweries  and 
distilleries,  also  tend  to  increase  the  odors,  while  others  which  decompose 
slowly  intensify  the  troubles  of  sedimentation  and  sludge  disposal.  The  sew¬ 
age  of  each  city  thus  has  a  specific  character  which  varies  with  the  nature 
and  magnitude  of  the  industries  pursued,  and  hence  a  method  of  treatment 
that  is  successful  at  one  time  may  require  extensive  modification  at  another. 

The  process  of  oxidizing  the  effluent  from  a  sedimentation  or  septic 
tank  is  usually  done  by  exposing  it  to  the  action  of  the  air  and  certain  micro¬ 
organisms  contained  in  so-called  “contact  beds”  or  “sprinkling  filters,”  which 
are  essentially  large  masses  of  very  porous  inorganic  material  like  coke,  furnace 
slag,  pebbles  and  broken  stone.  Experiments  at  Columbus,  O.,  have  shown 
that  beds  of  this  kind  5  ft.  in  depth  can  effect  the  oxidation  of  only  a  limited 
quantity  of  dissolved  organic  matter,  and  that  the  liquid  should  not  be 
applied  at  greater  rates  than  700,000  gallons  per  acre  daily  to  contact  beds, 
and  2,000,000  gallons  per  acre  daily  to  sprinkling  filters.  In  both  cases  the 
beds  must  obviously  be  thoroughly  underdrained.  If  contact  beds  are  used, 
they  can  be  filled  without  much  fall  or  loss  of  head  directly  from  the  sedi¬ 
mentation  tanks ;  but  in  the  case  of  sprinkling  filters,  the  top  of  the  beds  must 


36 


be  from  4  to  8  feet  lower  than  the  surface  of  the  liquid  in  the  effluent  channel 
from  the  tanks  in  order  to  form  a  proper  spray.  This  latter  condition  thus 
involves  a  location  on  sloping  ground,  or  else  the  cost  of  deep  excavation  for 
constructing  and  underdraining  the  filters,  or  the  cost  of  pumping  the  liquid 
after  leaving  the  sedimentation  tanks.  ^ 

It  should  also  be  noted  that  the  effluents  from  contact  beds  and  sprinkling 
filters  are  usually  somewhat  turbid,  and  that  if  a  clear  water  is  desired,  they 
must  be  further  purified  by  filtration  through  natural  or  artificial  beds  of  sand 
or  fine  gravel,  or  by  settling  for  several  hours  in  another  set  of  tanks.  This 
finishing  process  involves  an  additional  fall  or  loss  of  head,  as  well  as  a 
large  additional  cost  for  filters  or  tanks.  If  sand  filters  are  used,  the  rate  of 
application  will  probably  not  exceed  1,000,000  gallons  of  the  effluent  from  the 
final  settling  tanks  per  acre  daily  on  the  average,  as  the  material  is  apt  to- 
become  clogged. 

For  the  treatment  of  the  sewage  of  Columbus,  O.,  the  recommendations 
made  in  November,  1905,  were  as  follows :  “1.  Preliminary  clarification  of 

the  sewage  in  basins  holding  on  an  average  about  an  8-hour  flow,  and  operated 
on  the  basis  of  the  septic  treatment.  2.  Purification  of  the  septic  effluent  to 
a  non-putrescible  state  by  sprinkling  filters  at  an  average  net  rate  of  2,000,- 
000  gallons  per  acre  daily.  3.  Final  clarification  of  the  effluent  of  the  sprink¬ 
ling  filters  in  basins  holding  an  average  flow  of  about  two  hours.  This 
process  produces  a  non-putrescible  effluent  of  satisfactory  appearance,  and 
from  which  about  90  per  cent,  of  the  bacteria  in  the  raw  sewage  are 
removed.” 

Similar  recommendations  were  made  in  May,  1906,  for  the  treatment  of 
the  sewage  of  Baltimore,  Md.,  with  the  addition  that  the  effluent  from  the 
last  set  of  settling  basins  should  be  still  further  purified  by  intermittent  filtra¬ 
tion  through  artificial  sand  filters,  “by  which  substantially  all  the  remaining 
bacteria  and  fine  suspended  matter  are  removed,  so  that  the  final  effluent  is; 
clear  and  has  obtained  the  highest  practicable  degree  of  purity.” 

As  to  the  costs  of  these  methods  of  treatment,  it  is  obvious  that  they 
will  be  much  greater  than  those  of  the  simpler  method  which  is,  in  my  opinion, 
ample  and  entirely  satisfactory  for  Rochester.  For  the  proposed  Baltimore- 
plant  to  purify  75,000,000  gallons  of  sewage  per  day,  the  estimated  cost  was 
$3,283,250,  exclusive  of  the  cost  of  the  necessary  land,  and  the  annual  operat¬ 
ing  expenses  were  $115,500,  exclusive  of  interest  and  other  fixed  charges.  At 
the  same  rate  per  million  gallons,  the  cost  of  a  similar  plant  for  purifying 
27,000,000  gallons  of  sewage  at  Rochester  would  be  about  $1,204,000,  exclusive- 
of  the  necessary  land  and  the  system  of  conduits  for  intercepting  and  con¬ 
veying  the  sewage  to  the  works ;  and  if  the  plant  were  adapted  to  purify  an’ 
average  of  34,000,000  gallons  of  sewage  and  intercepted  storm  water  per  day 
from  the  assumed  future  population  of  275,000,  the  costs  would  be  still 
greater. 

In  view  of  the  great  expense  of  these  refined  modern  methods  of  purify¬ 
ing  sewage,  and  the  availability  at  Rochester  of  much  cheaper  ones  that  will 
doubtless  prove  to  be  entirely  satisfactory  for  many  years,  the  writer  has 
deemed  it  unnecessary  to  submit  here  other  details  relating  to  the  construc¬ 
tion,  operation  and  costs  of  contact  beds  and  sprinkling  filters.  To  those- 
familiar  with  the  capacity  of  the  river  and  lake  to  absorb  sewage  inoffensively,, 
the  necessity  for  resorting  to  an  extreme  purification  does  not  appear;  and 


37 


it  has  also  been  assumed  that  any  acceptable  plan  for  dealing  with  the  sewage 
of  the  City  should  involve  no  expenses  that  can  reasonably  be  avoided. 


COMPARISON  OF  COSTS  OF  SEWAGE  DISPOSAL. 

wc 

It  has  been  attempted  in  the  foregoing  to  describe  briefly  the  various  plans 
that  seemed  practicable  to  the  writer  for  improving  the  sewage-polluted  con¬ 
dition  of  the  Genesee  River  from  the  upper  falls  to  Lake  Ontario,  together 
with  the  probable  costs  of  construction  and  operation,  based  on  an  assumed 
population  of  275,000  in  the  year  1925  ;  and  it  now  becomes  of  interest  to  make 
a  short  summary  of  such  methods  and  costs.  These  plans  fall  into  two 
general  classes,  one  involving  an  adequate  increase  of  the  minimum  flow  of 
the  river  above  the  City,  so  as  to  allow  the  existing  principal  outlet  sewers 
to  continue  to  discharge  their  contents  directly  into  the  stream  as  at  present, 
and  the  other  involving  an  interception  and  removal  of  the  dry-weather  flow 
of  said  sewers  to  other  localities.  The  first  class  embraces  two  plans,  while 
the  second  embraces  four. 

1.  Constant  Dilution  by  Means  of  Storage  Reservoir. 

Cost  of  storage  reservoir  at  Portage  or  Mt.  Morris,  as  per  estimates  of 
State  Engineer  in  1894  and  1896,  from  $2,500,000  to  $2,600,000.  These  esti¬ 
mates  should  be  increased  considerably  to  meet  the  greater  present  values  of 
lands,  materials  and  labor.  This  plan  cannot  be  carried  out  independently 
by  the  city,  and  it  has  also  a  limited  applicability  as  the  minimum  flow  of  the 
river  will  then  not  become  more  than  1,000  cu.  ft.  per  second.  Even  if 
satisfactory  agreements  could  be  reached  between  the  city,  the  owners  of  the 
water-power,  and  the  State  in  behalf  of  the  canal  interests,  the  time  needed 
for  the  execution  of  the  work  is  much  longer  than  seems  to  be  tolerable. 
The  plan  is  accordingly  rejected. 

.2.  Periodical  Flushing  by  Smaller  Storage  Reservoir. 

Cost  of  storage  reservoir  of  relatively  small  capacity  near  Mt.  Morris 
.at  least  $900,000.  This  plan  also  involves  agreements  with  owners  of  water¬ 
power  and  the  State,  and  cannot  be  recommended  on  account  of  the  improb¬ 
ability  of  attaining  satisfactory  results. 

.3.  Constant  Flushing  of  the  Lower  River  by  Pumping  from  Lake  or  Bay. 

Cost  of  12  ft.  tunnel  4.66  miles  long  and  pumping  plant  to  secure  a  20-fold 
dilution  of  the  sewage  from  a  future  population  of  275,000,  $1,455,000;  annual 
•operating  expenses  for  120  days  per  year  $20,600.  With  a  14-fold  dilution  of 
the  sewage,  the  cost  of  10  ft.  tunnel  and  smaller  pumping  plant  would  be 
$1,214,000,  and  the  annual  operating  expenses  for  120  days  per  year  $16,000. 

In  both  of  these  cases,  the  cost  of  intercepting  the  dry-weather  flow  of 
sewage  from  the  several  outlet  sewers  which  discharge  into  the  river  above 
the  lower  falls,  has  not  been  included.  This  interception  may  become  a 
very  important  feature  hereafter,  and  if  it  is  not  done,  the  condition  of  the 
.8,500  ft.  of  river  channel  between  the  upper  and  lower  falls  may  become 


38 


intolerable.  The  least  expensive  plan  of  such  interception  would  be  by  means 
of  the  system  of  pipes  previously  described,  but  terminating  at  the  shaft  of 
the  West  Side  Trunk  Sewer,  and  costing  approximately  $210,000.  This  sum 
should  accordingly  be  added  to  the  above  estimates,  thus  making  the  same 
respectively  $1,665,000  and  $1,424,000. 

4.  Clarification  of  Sewage  by  Sedimentation  at  Works  Located  1.25 

Miles  North  of  Norton  Street. 

This  plan  involves  the  interception  of  the  dry-weather  flow  of  sewage 
from  all  the  principal  outlet  sewers,  except  the  one  for  the  northern  district 
•of  Lake  Avenue.  Cost  of  system  of  intercepting  pipes  and  conduits  from 
upper  falls  to  intersection  of  Strong  and  Hollenbeck  streets,  including  West 
Side  Trunk  Sewer  pumping  station  and  10  per  cent,  for  contingencies,  $344,- 
■300 ;  cost  of  conduit  from  Strong  Street  to  sedimentation  plant,  and  also 
latter  complete,  adapted  to  treatment  of  34,000,000  gallons  of  sewage  per 
day,  including  electrical  power  development  for  100  H.  P.  and  transmission 
line  to  West  Side  Trunk  Sewer  pumping  station,  $324,000;  assumed  cost  of 
150  acres  of  land  for  plant  and  other  easements,  $101,700;  total  cost  $770,000. 
Operating  expenses  during  120  days  per  year,  for  sedimentation  of  an  aver¬ 
age  flow  of  34,000,000  gallons  of  sewage  and  storm  water  per  day,  disposal 
of  sludge  and  operation  of  West  Side  Trunk  Sewer  pumping  station  by 
■electrical  power,  $21,900;  but  as  the  time  named  may  be  exceeded  somewhat, 
it  will  be  safer  to  assume  that  the  yearly  operating  expenses  will  ultimately 
be  $25,000. 

With  respect  to  this  plan,  it  may  be  urged  that  the  establishment  of  a 
sewage  purification  works  so  near  to  the  present  northern  boundary  of  the 
•city  will  tend  to  stop  the  growth  of  the  city  in  this  direction ;  also  that  the 
partial  purification  contemplated  will  eventually  become  inadequate  unless  the 
dry-season  flow  of  the  river  is  largely  increased  either  by  water-storage 
■operations,  or  by  surplus  water  from  the  Barge  Canal.  It  may  likewise  be 
•expected  that  if  such  storage  operations  are  carried  out  in  the  future,  and  the 
sewage  is  only  partly  purified,  the  city  will  be  required  to  pay  a  portion  of 
the  expense  of  increasing  the  minimum  flow  of  the  river.  In  this  event  the 
•estimated  cost  of  the  plan  named  would  not  represent  the  ultimate  cost. 

5.  Clarification  of  Sewage  by  Chemical  Precipitation  at  Works 

Located  1.25  Miles  North  of  Norton  Street. 

This  plan  is  the  same  as  the  preceding  one  in  all  respects,  except  that  the 
•ultimate  annual  operating  expenses  are  $36,000.  Concerning  this  project,  it 
may  be  said  that  a  considerably  higher  degree  of  purification  will  be  effected 
than  by  plain  sedimentation,  and  hence  that  a  correspondingly  smaller  charge 
should  be  made  against  the  city  for  the  benefit  accruing  to  it  in  consequence 
•of  increasing  the  dry-season  flow  of  the  river.  While  the  equities  in  the  case 
might  readily  be  determined,  it  is  nevertheless  uncertain  how  the  interests 
•of  the  city  would  be  affected  by  legislation.  The  plan  is  therefore  invested 
with  some  risk  that  the  estimated  cost  will  ultimately  be  exceeded,  but  such 
risk  is  manifestly  smaller  than  in  the  preceding  case. 

Both  of  these  plans,  however,  possess  the  great  merit  of  being  elastic 


39 


from  a  financial  standpoint,  or  capable  of  development  from  time  to  time  as 
circumstances  may  require.  This  is  an  important  consideration  that  should 
not  be  overlooked. 

6.  Screening  and  Discharging  Sewage  into  Lake  Ontario,  East  of 
Windsor  Beach. 

This  plan  also  involves  the  interception  of  the  dry-weather  flow  of  sewage 
from  all  of  the  principal  outlet  sewers,  except  the  one  for  the  northern  district 
of  Lake  Avenue.  As  no  power  can  here  be  generated  from  the  sewage,  the 
discharge  of  the  West  Side  Trunk  Sewer  must  be  pumped  by  steam  power 
for  120  days  per  year  at  a  cost  of  $4,000.  The  screening  must  be  done 
throughout  the  year  at  a  cost  of  $8,000.  Cost  of  system  of  intercepting  pipes 
and  conduits  from  upper  falls  to  intersection  of  Strong  and  Hollenbeck 
streets,  including  West  Side  Trunk  Sewer  pumping  station  and  10  per  cent, 
for  contingencies,  $344,300;  cost  of  masonry  conduit  from  Strong  Street  to 
shore  of  lake  and  subrnerged  outlet  pipe,  $572,000;  assumed  cost  of  about  100' 
acres  of  land  surrounding  screening  and  detritus  tank,  $38,000;  total  cost 
$954,300.  Annual  operating  expenses  as  above,  $12,000. 

In  this  project,  the  great  advantage  is  secured  of  excluding  the  normal 
flow  of  sewage  from  the  river  throughout  the  entire  year,  thereby  rendering 
the  lower  portion  of  the  stream  unquestionably  salubrious  and  attractive  for 
pleasure  navigation.  The  sewage  will  be  permanently  out  of  sight,  and 
judging  from  the  experience  gained  in  other  large  cities  on  the  Great  Lakes, 
no  serious  contamination  of  the  lake  water  or  pollution  of  the  beaches  will 
ensue.  It  is  also  very  probable  that  a  considerable  reduction  of  cost  can  be 
secured  by  the  use  of  a  wooden  stave  pipe  for  the  long  submerged  outlet  in: 
place  of  the  riveted  steel  pipe. 


CHOICE  OF  PLAN. 

In  view  of  the  fact  that  any  water  storage  scheme  on  the  Genesee  River 
and  its  tributaries  cannot  be  carried  out  by  the  city  independently,  and  also- 
owing  to  the  long  time  needed  therefor,  the  first  and  second  plans  described 
above  cannot  be  considered,  and  the  choice  is  therefore  restricted  to  the 
remaining  four.  To  facilitate  comparison,  the  annual  operating  expenses 
may  be  capitalized  at  5  per  cent.,  and  the  corresponding  principals  added  to  the 
estimated  costs  of  construction  and  land  in  each  case,  whereby  the  following, 
results  will  be  obtained.  It  should  also  be  noted  that  these  results  apply  to 
the  conditions  presumed  to  exist  about  20  years  hence  when  the  population 
reaches  275,000,  and  embrace  the  costs  of  the  system  of  intercepting  pipes 
and  conduits. 


For  20-fold  dilution  of  sewage  by  pumping .  $2,077,000* 

For  14-fold  dilution  of  sewage  by  pumping .  $1,744,000 

For  clarification  of  sewage  by  sedimentation .  $1,270,000 

For  clarification  of  sewage  by  precipitation .  $1,490,000 

For  discharge  of  sewage  into  Lake  Ontario .  $1,194,300) 


40 


It  is  understood  that  in  each  instance  the  annual  operating  expenses 
mentioned  do  not  include  the  usual  fixed  charges  consisting  of  interest  on 
capital  expended  for  construction  and  land,  depreciation  of  plant,  taxes, 
insurance  and  sinking  fund. 

From  this  comparison  it  is  seen  that  the  plan  of  discharging  the  sewage 
into  Lake  Ontario  is  the  least  costly,  and  probably  also  the  most  satisfactory 
one,  in  view  of  the  existing  prejudices  against  sewage  purification  works  and 
the  utilization  of  either  screened  or  clarified  sewage  for  agriculture.  If  these 
prejudices  could  be  overcome  and  the  citizens  would  be  content  with  an 
inoffensive  contamination  of  the  water  of  the  lower  river,  the  plan  of  par¬ 
tially  purifying  the  sewage  during  the  dry-season  at  a  point  about  1.25  miles 
north  of  Norton  Street  would  become  more  expedient  for  adoption,  as  the 
accumulation  of  savings  in  annual  operating  expenses  and  fixed  charges  on 
the  much  smaller  costs  of  construction  during  20  years  or  more  would  over¬ 
balance  the  apparent  difference  shown  above. 

In  further  support  of  the  latter  process,  it  may  be  remarked  that  advances 
in  the  art  of  treating  sewage  will  doubtless  be  made  in  the  next  20  years, 
whereby  the  great  expense  of  sprinkling  filters  or  contact  beds,  and  the 
subsequent  clarification  of  the  effluent,  will  be  avoided  when  a  large  river 
is  available  as  an  outfall.  It  may  also  be  expected  that  the  dry-season  flow 
of  the  river  will  be  increased  by  a  considerable  quantity  of  surplus  water 
from  the  Barge  Canal,  which  will  assist  very  materially  in  the  required 
dilution  of  the  effluent  from  the  sedimentation  tanks;  and  if  the  project  of 
storing  water  at  Portage  or  Mt.  Morris  is  meanwhile  carried  out,  there  will 
be  no  necessity  for  any  treatment  of  the  sewage  until  the  population  greatly 
■exceeds  the  limit  mentioned. 

Should  any  of  these  expectations  be  realized,  it  will  follow  that  the  plan 
of  treating  the  sewage  in  the  manner  indicated  near  the  present  northern 
boundary  of  the  city  will  involve  the  least  aggregate  outlay,  and  will  also 
have  the  highest  salvage  value  in  case  of  voluntary  abandonment  or  enforced 
modification.  Thus  if  it  should  ever  become  necessary  to  subject  the  crude 
sewage  at  the  lake  shore  to  any  better  treatment  than  screening,  such  work 
can  manifestly  be  done  far  more  economically  at  the  site  first  named.  It  may 
also  be  added  that  for  the  performance  of  such  work,  the  said  site  is  much 
better  adapted  in  all  respects  than  any  other  site  in  the  entire  region. 

In  the  plan  for  carrying  the  sewage  to  Lake  Ontario,  it  was  deemed  proper 
to  provide  for  intercepting  the  dry-weather  flow  and  a  part  of  the  storm 
water  of  all  the  principal  outlet  sewers  on  both  sides  of  the  river,  except  the 
■one  for  the  northern  district  of  Lake  Avenue.  Any  permanent  modification 
of  this  plan  by  permitting  some  of  these  outlet  sewers  to  continue  to  dis¬ 
charge  into  the  river,  and  thereby  reduce  the  size  of  the  conduit  to  the  lake 
shore,  is  not  advisable,  as  the  difference  in  cost  is  not  large  enough  to  out¬ 
weigh  the  disadvantage  of  maintaining  a  continuous  pollution  of  the  stream, 
■especially  between  the  upper  and  lower  falls.  The  same  remark  is  still  more 
applicable  to  the  rival  plan  of  partially  purifying  the  sewage  at  the  aforesaid 
site. 

This  statement,  however,  should  not  be  construed  to  mean  that  it  is 
imperative  to  perform  the  whole  of  the  work  of  interception  at  once,  or  even 
in  a  single  year,  but  rather  that  it  be  planned  with  the  view  of  embracing  the 
.sewage  of  practically  the  entire  future  city,  and  proceed  from  time  to  time 


41 


as  circumstances  may  require.  It  will  naturally  begin  with  the  diversion  of 
the  normal  flow  of  the  East  Side  Trunk  Sewer,  and  be  followed  by  the  con¬ 
duit  and  tunnel  to  the  foot  of  Avenue  B.  Next  in  order  will  be  the  inter¬ 
ception  of  the  West  Side  Trunk  Sewer,  if  the  anticipated  industrial  devel¬ 
opment  of  the  western  part  of  the  city  and  the  adjacent  part  of  the  Town 
of  Gates  takes  place ;  otherwise  the  next  step  will  be  the  interception  of  the 
Platt  Street  and  Spencer  Street  outlet  sewers.  The  last  step  is  the  intercep¬ 
tion  of  the  Central  Avenue  and  Front  Street  outlet  sewers,  and  perhaps, 
also  the  Lake  Avenue  outlet. 


CONCLUSION  AND  RECOMMENDATIONS. 

After  careful  consideration  of  the  several  plans  that  have  been  described' 
and  discussed  in  the  foregoing,  the  undersigned  has  reached  the  conclusion 
that  preference  should  be  given  to  the  project  for  discharging  the  crude  sew¬ 
age  of  the  city  into  Lake  Ontario.  Although  somewhat  more  expensive 
in  first  cost  than  the  plan  involving  sedimentation  and  chemical  treatment,  it 
has  the  great  advantage  of  simplicity  of  management  and  independence  of  the 
exercise  of  constant  skillful  supervision.  The  latter  is  not  always  available,, 
and  its  absence  for  any  reason  may  lead  to  unpleasant  results,  both  with 
respect  to  the  condition  of  the  river  and  to  the  development  of  disagreeable 
odors  by  the  works.  Under  such  conditions  the  difference  in  cost  may 
quickly  disappear  by  expenditures  for  damages  and  futile  experiments. 

With  reference  to  freedom  from  the  production  of  offensive  conditions 
at  the  lake,  little  further  can  be  said  than  was  set  forth  above.  In  the 
vicinity  of  the  mouth  of  the  river,  the  water  will  always  be  more  or  less 
contaminated  from  the  surface  drainage  of  the  entire  watershed,  and  it  is 
difficult  to  see  how  this  will  be  aggravated  materially  by  the  discharge  of  the 
screened  sewage  into  deep  water  so  far  from  shore.  It  should  also  be 
remembered  that  the  outlet  pipe  can  readily  be  extended  to  a  much  greater 
distance  than  7,000  ft.  without  involving  a  proportionally  greater  cost,  as  a 
large  percentage  of  the  estimated  expense  for  this  pipe  is  for  accessory 
appliances  and  constructions  that  will  not  be  needed  in  making  a  future 
extension. 

Furthermore,  the  exact  location  of  the  mouth  of  the  outlet  pipe  has  not 
yet  been  definitely  fixed,  as  the  most  recent  available  hydrographic  chart  of 
the  U.  S.  Lake  Survey  showing  soundings  along  this  portion  of  the  shore 
was  made  several  years  ago,  and  it  is  possible  that  new  surveys  will  show 
that  a  depth  of  45  ft.  occurs  somewhat  farther  out.  It  may  also  be  added 
that  the  estimates  have  been  made  on  a  sufficiently  liberal  basis  to  admit  of 
extending  the  pipe  1,000  ft.,  provided  that  due  economy  is  exercised  in  the 
prosecution  of  the  work. 

As  the  sewers  will  continue  to  discharge  storm  water  in  the  future,  as 
in  the  past,  it  need  scarcely  be  said  that  proper  attention  should  constantly  be 
given  to  keep  the  outlets  and  the  adjacent  river  channel  in  good  order. 
This  has  not  been  done  at  the  mouth  of  the  East  Side  Trunk  Sewer,  in 
consequence  of  which  the  small  channel  into  which  it  discharges  has  become 
very  foul.  If  the  channel  were  dredged  out  so  as  to  carry  at  least  one-half 


42 


of  the  ordinary  flow  of  the  river,  the  unsightly  conditions  at  this  place 
would  soon  disappear. 

Attention  may  also  be  called  to  the  necessity  for  a  systematic  cleaning  of 
the  sewers,  as  neglect  in  this  respect  gives  rise  to  offensive  emanations  at  all 
openings.  In  cities  where  the  sewers  are  kept  clean  by  proper  flushing,  there 
is  little  complaint  about  disagreeable  odors  from  manholes  and  catch-basins. 
At  the  places  where  sewers  pass  under  the  Erie  Canal,  such  flushing  can 
easily  be  done  with  canal  water  at  regular  intervals  by  means  of  siphons, 
and  as  the  quantity  of  water  needed  for  the  purpose  is  comparatively  small, 
the  consent  of  the  canal  authorities  for  such  occasional  use  should  readily 
be  obtained. 

In  concluding  this  report,  the  writer  takes  pleasure  in  acknowledging 
his  indebtedness  to  City  Engineer  Edwin  A.  Fisher  for  many  courtesies  and 
valuable  suggestions,  as  well  as  for  the  preparation  of  numerous  necessary 
maps  and  data  which  have  greatly  facilitated  the  study  of  the  problem. 

Respectfully  submitted, 

E.  KUICHLING, 
Consulting  Engineer. 


Cincinnati,  Ohio,  Feb.  6,  1907. 

Hon.  James  G.  Cutler,  Mayor, 

City  of  Rochester,  N.  Y. 

Dear  Sir : — The  undersigned,  having  at  your  request  carefully  considered 
with  Mr.  Emil  Kuichling  the  subject  of  his  report  on  the  disposal  of  the 
sewage  of  the  City  of  Rochester,  after  a  study  of  the  data  and  information 
collected  by  him  which  have  any  bearing  thereupon  and  after  several  long 
conferences  with  him  and  Mr.  E.  A.  Fisher,  your  City  Engineer,  in  both 
New  York  and  Rochester  and  after  a  personal  inspection  of  the  river,  the 
lake  and  the  territory  north  of  the  City,  and  having  in  mind  your  instructions 
to  recommend  to  you  the  best  method,  all  things  considered,  for  disposing  of 
the  sewage  of  the  City  of  Rochester,  we  desire  herewith  to  state  that  we 
fully  concur  in  the  conclusion  and  recommendations  expressed  in  the  foregoing 
report,  as  submitted  by  Mr.  Emil  Kuichling,  being  of  the  firm  belief  that  the 
permanent  exclusion  from  the  river  of  all  sewage  proper  and  the  discharge 
of  the  same  at  a  long  distance  from  the  shore  and  at  a  considerable  depth 
into  cold  water,  after  all  floating  material  has  been  previously  removed,  will, 
all  things  considered,  secure  to  your  people  the  most  satisfactory  solution  of 
the  problem. 

Respectfully  submitted, 

G.  H.  BENZENBERG, 
RUDOLPH  HERING, 

Consulting  Engineers. 


43 


CONTENTS 


Page. 

Letter  of  transmittal  . 3 

Population  and  area  of  city  . 5 

Outlet  sewers,  with  tributary  areas  and  population  . 6 

Elevations  of  sewer  inverts  at  outlets  . 7 

Dry-season  flow  of  Genesee  River  . 9 

Disposal  of  sewage  by  dilution  in  river  . 9 

Increasing  low-water  flow  of  river  by  storage  . • . 12 

Increasing  low-water  flow  of  river  by  pumping  from  lake  or  bay . 14 

Quantity  of  sewage  produced  in  city  . . 16 

Mechanical  and  chemical  clarification  of  sewage  . 17 

Interception  of  principal  outlet  sewers . 21 

Costs  of  mechanical  and  chemical  clarification  of  the  sewage  of  Rochester .  .24 

Comments  on  mechanical  and  chemical  clarification  process . 27 

Availability  of  clarified  sewage  for  power  and  irrigation.... . 29 

Discharge  of  crude  sewage  into  Lake  Ontario . 31 

Other  methods  of  sewage  treatment  . . 35 

Comparison  of  costs  of  various  plans  of  sewage  disposal . 38 

Choice  of  plan  of  sewage  disposal  for  city . 40 

Conclusion  and  recommendations  . 42 

Concurrence  of  Consulting  Engineers  . 43 


UNIVERSITY  OF  ILUNOIS-URBANA 


N30 1121 04323578A 


